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Norih ouroiina Stare Library 

North Carolina jyj e Q, 

Department of Conservation and Development 
Dan E. Stewart, Director 


Division of Mineral Resources 
Stephen G. Conrad, State Geologist 

Bulletin 80 

Pyrophyllite Deposits 

in North Carolina 

Jasper L. Stuckey 


Digitized by the Internet Archive 

in 2013 

North Carolina 

Department of Conservation and Development 

Dan E. Stewart, Director 

Division of Mineral Resources 
Stephen G. Conrad, State Geologist 

Bulletin 80 

Pyrophyllite Deposits 

in North Carolina 

Jasper L. Stuckey 



James W. York, Chairman Raleigh 

R. Patrick Spangler, First Vice Chairman Shelby 

William P. Saunders, Second Vice Chairman Southern Pines 

John M. Akers Gastonia 

John K. Barrow, Jr. Ahoskie 

J. 0. Bishop Rocky Mount 

David Blanton Marion 

Harry D. Blomberg Asheville 

Robert E . Bryan Goldsboro 

William B. Carter Washington 

Arthur G. Corpening, Jr. . High Point 

Moncie L. Daniels, Jr. Manteo 

Koy E . D awkins Monroe 

Dr. J. A. Gill Elizabeth City 

John Harden . Greensboro 

Gilliam K. Horton Wilmington 

Dr. Henry W. Jordan Cedar Falls 

Petro Kulynych Wilkesboro 

William H. Maynard Lenoir 

W. H. McDonald Tryon 

Jack Pait Lumberton 

John A. Parris, Jr. Sylva 

Oscar J. Sikes, Jr. Albemarle 

T. Max Watson Spindale 



Raleigh, North Carolina 
March 1, 1967 

To His Excellency, HONORABLE DAN K. MOORE 
Governor of North Carolina 


I have the honor to submit herewith manuscript for publication as 
Bulletin 80, "Pyrophyllite Deposits in North Carolina," by Jasper L. 

This report contains detailed information on the occurrence, distri- 
bution and geology of pyrophyllite in North Carolina and should prove 
to be of considerable value to those interested in the mining and 
processing of this valuable mineral resource. 

Respectfully submitted, 





Abstract 1 

Introduction 1 

Previous work 1 

Geology of the Carolina Slate belt 4 

General statement 4 

Distribution and character of the rocks 4 

Felsic volcanic rocks 5 

Mafic volcanic rocks 6 

Bedded argillites (volcanic slate) 6 

Igneous intrusive rocks 7 

Environment of deposition 7 

Structural features 7 

Age of the rocks 8 

Geology of the pyrophyllite deposits 9 

Introduction 9 

Distribution 10 

Geologic relations 11 

Form and structure 11 

Mineralogy of the deposits 12 

Pyrophyllite 12 

Quartz 12 

Sericite 12 

Chloritoid 12 

Pyrite 13 

Chlorite 13 

Feldspar 13 

Iron oxides 13 

High alumina minerals 13 

Petrography 13 

Origin of the pyrophyllite deposits 14 

Earlier theories 14 

Analyses of rocks 16 

Origin of North Carolina pyrophyllite 18 

Source of mineralizing solutions 18 

Conditions of pyrophyllite formation 19 

Reserves 19 

Mining methods 20 

Processing 21 

Uses of pyrophyllite 21 

Mines and prospects 23 

Granville County 23 

Daniels Mountain 23 

Bowlings Mountain 23 


Long Mountain 24 

Robbins prospect No. 1 24 

Jones prospect 24 

R. E. Hilton property 24 

E. C. Hilton property 24 

Robins-Uzzell property 25 

Robbins prospect No. 2 25 

Orange County 25 

Murray prospect 25 

Hillsborough mine 25 

Teer prospects 25 

Alamance County 27 

Snow Camp mine 27 

Major Hill prospects • 27 

Chatham County 28 

Hinshaw prospect 28 

Randolph County 28 

Staley deposit 28 

Pilot Mountain prospects 28 

Moore County 29 

McConnell prospect 29 

Jackson prospect 30 

Bates mine 30 

Phillips mine 30 

Womble mine . .31 

Reaves mine 31 

Jones prospect 33 

Currie prospect 33 

Ruff prospect 33 

Hallison prospect 33 

Standard Mineral Company 33 

Tucker and Williams pits 35 

Sanders prospect . .35 

Montgomery County 36 

Ammons mine 36 

North State property 1 36 

North State property 2 36 

Cotton Stone Mountain 37 

Standard Mineral Company 37 

References cited 37 



Plate 1. Pyrophyllite deposits in North Carolina 23 

2. Piedmont Minerals Company 26 

A. Mill 

B. Open pit mine 

3. Glendon Pyrophyllite Company 32 

A. Mill 

B. Open pit mine (Reaves) 

4. Standard Mineral Company 34 

A. Mill 

B. Open pit mine 


Pyrophyllite Deposits of North Carolina 


Jasper L. Stuckey 


All the known occurrences of pyrophyllite in North Carolina are found in Granville, Orange, 
Alamance, Chatham, Randolph, Moore and Montgomery counties where they are associated with vol- 
canic-sedimentary rocks of the Carolina Slate Belt. These rocks consist of lava flows interbedded with 
beds of ash, tuff, breccia and shale or slate that vary in composition from rhyolitic, or acid, to andesitic, 
or basic, and fall into three natural groups : Felsic Volcanics, Mafic Volcanics, and Bedded Argillites 
(Volcanic Slate). They have been folded, faulted and metamorphosed to the extent that they contain 
a well defined cleavage that strikes northeast and dips, in general, to the northwest. 

The pyrophyllite deposits which are irregular, oval or lens-like in form occur in acid volcanic rocks 
that vary from rhyolite to dacite in composition. The field, microscopic and chemical evidence indicates 
that the pyrophyllite bodies were formed by metasomatic replacement of the host rocks through the 
agency of hydrothermal solutions under conditions of intermediate temperature and pressure. 

Pyrophyllite has a variety of uses chief of which are in paints, rubber goods, roofing materials, 
ceramic products and insecticides. Reserves, while not large, are ample for several years. 


The pyrophyllite deposits of North Carolina are 
associated with volcanic-sedimentary rocks of the 
Carolina Slate Belt. Volcanic-sedimentary and 
similar rocks form a belt or zone along the east- 
ern border of the Piedmont Plateau and parts 
of the Coastal Plain all the way from the vicinity 
of Petersburg and Farmville, Virginia, southwest 
across North Carolina, South Carolina and into 
Georgia, as far as the southern part of Baldwin 
County south of Milledgeville — a total distance 
of over 400 miles. In North Carolina the zone 
occupied by volcanic-sedimentary rocks is known 
as the Carolina Slate Belt. It is in this belt that 
the pyrophyllite deposits of the state are found. 

The western border of the Carolina Slate Belt 
lies a few miles east of Charlotte, Lexington and 
Thomasville, crosses Guilford County southeast 
of Greensboro and continues northeast across the 
northwest corner of Alamance and Orange coun- 
ties and the center of Person County to the Vir- 
ginia line. The eastern limits of this belt are 
marked, by the cover of Coastal Plain sediments. 


Due to the presence of a wide variety of min- 
erals in them, the rocks of the Carolina Slate 
Belt have been of interest for approximately 150 
years. These rocks, because of their complex 

character and well developed cleavage, were 
called slates by a number of investigators over a 
period of 70 years before their true nature began 
to be recognized. The first published report on 
that part of the slate belt in which pyrophyllite 
deposits are known to occur was a descriptive list 
of rocks and minerals from North Carolina by 
Denison Olmsted (1822). In this list he de- 
scribed novaculite, slate, hornstone, whetstone 
and talc and soapstone from several counties in- 
cluding Orange and Chatham. He stated that the 
talc and soapstone were extensively used for 
building and ornamental purposes and added that 
Indian utensils of the same materials were com- 

In 1823, Olmsted was appointed by the Board 
of Agriculture to make a geological survey of the 
State. In his first report (1825) he called atten- 
tion to the "Great Slate Formation which passes 
quite across the State from northeast to south- 
west covering more or less of the counties of 
Person, Orange, Chatham, Montgomery — ." The 
presence of talc and soapstone was noted in 
Orange, Chatham and other counties together 
with beds of porphyry in the eastern part of the 
formation and bands of breccia consisting of 
rolled pebbles interbedded in a ferruginous green- 
stone in different places. 

Ebenezer Emmons (1856), one of the most 
competent geologists of his time, considered the 

Carolina Slate Belt rocks to be among the oldest 
in the country and placed them in his Taconic 
system which he divided into an upper and lower 
member. The upper member consisted of clay 
slates, chloritic sandstones, cherty beds and brec- 
ciated conglomerate. The lbwer member consisted 
of talcose slates, white and brown quartzites and 
conglomerate. He did not recognize the presence 
of volcanic rocks in what is now known as the 
Carolina Slate Belt. In his lower unit, Emmons 
found what he considered to be fossils and named 
them Paleotrochis major and Paleotrochis minor. 
Diller (1899) recognized these as spherulites in 

Emmons described in some detail the phyro- 
phyllite deposits near Glendon, Moore County, 
then known as Hancock's Mill and classed the 
talcose slates, or those containing the pyrophyl- 
lite, as the basal member or oldest rocks of his 
Taconic system. He further pointed out that pyro- 
phyllite occurred in the same position in Mont- 
gomery County. 

Prior to this time the pyrophyllite had been 
considered as soapstone, but Emmons tested it 
before the blowpipe and found it to contain alumi- 
num and classed it as agalmatolite. He gave the 
physical properties of this mineral together with 
its uses and the methods of mining near Han- 
cock's Mill. Brush (1862) analyzed some of the 
material from Hancock's Mill, Moore County and 
showed it to be pyrophyllite. 

Kerr (1875) placed the rocks of the slate belt 
in the Huronian, which in his classification is a 
division of the Archean and considered them to 
be sedimentary. He mentioned talc and soapstone 
from Orange and Chatham counties but added 
nothing to the description already published by 

Kerr and Hanna (1893) in "Ores of North 
Carolina," described some old gold mines in the 
Deep River region and stated: "It is worthwhile 
to add that part of what passes for talc is pyro- 
phyllite and even hydromicaceous." 

Williams (1894) recognized for the first time 
the occurrence of ancient acid volcanic rocks in 
the slate belt. He studied a small area in Chatham 
County and applied for the first time modern 
petrographic methods to the study of these rocks. 
He described this area in part as follows : "Here 
are to be seen admirable exposures of volcanic 
flows and breccias with finer tuff deposits which 
have been sheared into slates by dynamic agen- 

cies." He classed the slate belt rocks as Precam- 
brian in age. 

Nitze and Hanna (1896) first used the name 
Carolina Slate Belt for the rocks Olmsted (1825) 
had designated the "Great Slate Formation." 
They recognized the occurrence of volcanic rocks 
in the slate belt and suggested that there had 
been more than one volcanic outbreak and during 
at least one period of inactivity slates had been 
deposited. They did not mention pyrophyllite but 
described in some detail the Bell, Burns and 
Cagle gold mines, all of which are in the pyro- 
phyllite area along Deep River in Moore County 
and pointed out that there had been much silicifi- 
cation at all of these and some propylitic altera- 
tion at the Bell mine in particular. 

Pratt (1900) described the pyrophyllite de- 
posits near Glendon and showed by chemical 
analysis that the mineral is true pyrophyllite. He 
described the pyrophyllite deposits as follows: 
"They are associated with the slates of this region 
but are not in direct contact with them, being 
usually separated by bands of siliceous and iron 
breccia which are probably 100 to 150 feet thick. 
These bands contain more or less pyrophyllite 
and they merge into a stratum of pyrophyllite 
schists." He offered no suggestion as to the origin 
of either the slates, breccia or pyrophyllite. 

Weed and Watson (1906) in a report on "The 
Virgilina Copper District," concluded that the 
rocks of that area were Precambrian volcanics, 
chiefly an original andesite that had been greatly 
altered by pressure and chemical metamorphism. 

Laney (1910) presented a report on the "Gold 
Hill Mining District of North Carolina," in which 
he stated: "The rocks here included under the 
general term slates while having many local vari- 
ations seem clearly to represent a great sedi- 
mentary series of shales with which are inter- 
bedded volcanic flows, breccias and tuffs. In their 
fresh and massive condition the slates are dense, 
bluish rocks which show in many places well 
defined bedding planes and laminations. The vol- 
canic flows, breccias and tuffs which are inter- 
bedded with the slates apparently represent two 
kinds of lava, a rhyolitic and an andesitic type." 

Pogue (1910) presented a report on the "Cid 
Mining District of Davidson County," in which 
he described the rocks of that area as follows: 
"Wide bands of sedimentary, slate-like rock, com- 
posed of varying admixtures of volcanic ash and 
land waste have the greatest areal extents. Inter- 
calated with these occur strips and lenses of acid 

and basic volcanic rocks, represented by fine and 
coarse-grained volcanic ejecta and old lava flows." 

Laney (1917) in a report on the Virgilina dis- 
trict classed the rocks in the area studied as 
volcanic-sedimentary and stated: "Under this 
group are placed both the acid and basic flows 
and tuffs and the water laid tuffs and slates." 

Stuckey (1928) presented a report on the Deep 
River region of Moore County in which he di- 
vided the rocks of the Carolina Slate Belt in that 
area into slates, acid tuffs, rhyolites, volcanic 
breccias and andesite flows and tuffs. He noted 
that the schistosity dipped to the northwest and 
interpreted the structure as a closely compressed 
synclinorium with axes of the folds parallel to the 
strike of the formations. In addition, he pointed 
out that metamorphism is not uniform through- 
out the area. 

Bowman (1954) studied the structure of the 
Carolina Slate Belt near Albemarle, North Caro- 
lina, and recognized sedimentary rocks, volcanic 
tuffs and flows, and mafic intrusives in the area. 
He interpreted the structure as a series of undu- 
lating open folds. 

Conley (1959); Stromquist and Conley, 1959; 
and Conley (1962 b) divided the rocks in the 
Albemarle and Denton 15-minute quadrangles 
into (1) a lower volcanic sequence consisting 
largely of felsic tuffs that have been folded into 
an anticline plunging to the southwest, (2) a 
volcanic-sedimentary sequence consisting of a 
lower argillite unit, an intermediate tuffaceous 
argillite unit and an upper graywacke unit which 
have been folded into a syncline also plunging to 
the southwest and (3) an upper volcanic sequence 
consisting of mafic and felsic volcanic rocks which 
unconformably overlie the first two sequences. 

According to Conley (1962 a), "In Moore 
County only the lower and middle units appear to 
be present; however, some rhyolite in the area 
might belong to the upper unit. The exact strati- 
graphic relationships of some of the rocks in the 
county are in doubt because of the gradational 
nature of the contacts, a condition further com- 
plicated by intense folding and faulting and lack 
of outcrops." 

Conley and Bain (1965) suggested that the 
rocks of the Carolina Slate Belt in North Carolina 
can be divided into natural, mappable rock units. 
They proposed and named a set of rock units or 
formations into which these rocks might be 
divided, gave their areal extent and described 

their structure and lithology. From oldest to 
youngest these proposed formations are: 

Morrow Mountain rhyolite 

Badin greenstone Tater Top Group 


Yadkin graywacke 
McManus formation 
Tillery formation 

Efland formation 
Uwharrie formation 

Albemarle Group 

The Uwharrie formation is composed chiefly of 
subaerially deposited felsic pyroclastic rocks. 
These are felsic tuffs consisting of interbedded 
lithic, lithic-crystal and devitrified vitric-crystal 
tuffs, welded flow tuffs and rhyolite. 

The Efland formation is a water-laid sequence 
consisting of andesitic tuffs with interbedded 
greenstones, conglomerates, graywackes and 

The Albemarle Group is a water-laid sequence 
of pyroclastics and sediments which is divided 
into the Tillery formation, the McManus forma- 
tion and the Yadkin graywacke. 

The Tillery formation is composed in part of 
finely laminated argillite exhibiting graded bed- 
ding and in part of andesitic tuff and greenstone. 

The McManus formation is predominantly a 
felsic tuffaceous argillite formerly known as the 
Monroe slate. 

The Yadkin graywacke is a dark-green gray- 
wacke sandstone containing interbeds of mafic 
tuffaceous argillite, mafic lithic-crystal tuff and 
felsic lithic tuff. 

The older rocks are in part unconformably 
overlain by subaerially deposited pyroclastics and 
flows known as the Tater Top Group. From base 
to top the group is composed of basaltic tuffs and 
flows overlain by rhyolite flows. The Tater Top 
Group is divided into the Badin greenstone and 
Morrow Mountain rhyolite. 

The Badin greenstone is composed of lithic 
crystal tuffs and a basal unit of flows and flow 
tuffs of andesitic composition. 

The Morrow Mountain rhyolite consists of 
dark-gray to black porphyritic rhyolite contain- 
ing prominent flow banding. 

Conley and Bain described the Troy anticli- 
norium, with a northeast-southwest trend, as the 
major structural feature of the Carolina Slate 
belt. West and southwest of the Troy anticlinori- 


um, northeast trending open folded synclines and 
anticlines predominate. East of the Troy anticli- 
norium the rocks are more intensely folded. They 
are compressed into northeast trending asym- 
metric folds whose axial planes usually dip 
steeply to the northwest. In many places, argil- 
lite has been converted into slate and phyllite. 

They considered the age of Carolina Slate Belt 
rocks to be early Paleozoic. 



In North Carolina rocks of the Carolina Slate 
Belt actually form two belts that are separated 
by sedimentary rocks of the Durham, Deep River 
and Wadesboro Triassic basins and by the Roles- 
ville granite pluton and associated gneisses and 
schists. The first and most important of these and 
the one Olmsted (1825) first called the "Great 
Slate Formation" and Nitze and Hanna (1896) 
first called the Carolina Slate Belt lies to the west 
of the belt of Triassic rocks and varies in width 
from 20 to 60 miles. It is widest between Sanford 
and Lexington and narrows to the north and 
south. It crosses the central part of the State in 
a northeast-southwest direction from Anson and 
Union counties on the southwest to Granville, 
Person and Vance counties on the northeast and 
underlies all or parts of Anson, Union, Mecklen- 
burg, Cabarrus, Stanly, Montgomery, Moore, 
Chatham, Randolph, Davidson, Rowan, Guilford, 
Alamance, Orange, Durham, Person, Granville 
and Vance counties. This belt contains all the 
known pyrophyllite deposits in North Carolina 
and will be considered in detail below. 

The second belt in which Kerr (1875) first 
recognized metavolcanic rocks lies to the east of 
the belts of Triassic, igneous and metamorphic 
rocks. It begins in Anson County on the south, 
varies greatly in width and regularity and con- 
tinues in a northeast direction to Northampton 
County on the north. It is exposed at the surface 
in all or parts of Anson, Richmond, Moore, Har- 
nett, Lee, Wake, Johnston, Wayne, Wilson, Frank- 
lin, Nash, Halifax and Northampton counties. 

The eastern limits of this belt are unknown due 
to the cover of Coastal Plain sediments. A deep 
well in Camden County about 8 miles north of 
Elizabeth City, the county seat of Pasquotank 
County, penetrated rocks that are apparently of 

the Carolina Slate Belt. Two deep wells — one a 
few miles southeast of Kelly, Bladen County and 
the other 4 miles south of Atkinson, Pender Coun- 
ty — both penetrated Carolina Slate Belt rocks. 
West of a line from Elizabeth City to Atkinson, 
of the few wells that reached basement, some 
penetrated granite, some penetrated gneiss and 
schist and a few penetrated rocks of the Carolina 
Slate Belt. 

It is possible that if the crystalline floor be- 
neath Coastal Plains sediments was exposed, the 
types and percentages of rocks in this floor 
would not differ greatly from those found west 
of Coastal Plain sediments in Harnett, Johnston, 
Wake, Wilson, Franklin, Nash, Vance, Warren, 
Halifax and Northampton counties, where 
gneisses and schists, granites and rocks of the 
Carolina Slate Belt occur in about equal amounts. 

Pyrophyllite has not been found in this eastern 
zone of Carolina Slate Belt rocks and they are 
not considered further in this report. 


The rocks of the Carolina Slate Belt, west of 
the Durham, Deep River, and Wadesboro Triassic 
basins, consist of lava flows interbedded with 
beds of ash, tuff, breccia and shale or slate. All 
of these except the flows contain much nonvol- 
canic material in the form of mud, clay, silt, sand 
and conglomerate. (Also present is much non- 
descript material, some of which may be vol- 
canic, which for the lack of a better term has 
been designated land waste) . The flows, breccias, 
tuffs and ash beds and beds of shale or slate are 
all interbedded and in general do not appear to 
occupy definite stratigraphic positions in the 
series. The flows vary from rhyolite through 
andesite to basalt. The rhyolites and andesites 
vary from fine grained to coarsely porphyritic 
whereas the basalts are often amygdaloidal. The 
breccias vary from rhyolitic to andesitic in com- 
position and in fragment size from one-half inch 
to nearly a foot in diameter. The fragments of 
the breccias are in turn fragmental, apparently 
pyroclastic in origin. Some of the fragments in 
the breccias are sharply angular, although many 
are rounded, indicating transportation and de- 
position. The tuffs, while containing both acid 
and basic materials, are in general of an acid 
composition and composed of fragments less than 
half an inch in diameter. These fragments which 

vary from angular to rounded are often embedded 
in much fine-grained material apparently of non- 
volcanic origin. 

Beginning in the vicinity of the Randolph- 
Chatham county line, 15 to 20 miles south of 
Siler City, and continuing northeast through 
Siler City to the northern part of Orange County 
and the southeastern part of Person County are 
a number of beds of quartz conglomerate varying 
in width from a few inches to as much as 250 
feet and of unknown length. The quartz pebbles 
in this conglomerate are generally less than an 
inch in diameter, well rounded and embedded in 
silt and sand, further indicating sedimentary 

The shales and slates, which are generally well 
bedded, are composed of fine-grained volcanic 
materials (and much land waste) in the form of 
clay, silt and fine sand. Finally, much of the fine- 
grained materials in the breccias, tuffs and por- 
tions of the shales and slates strongly resemble 
metasiltstone and metagraywacke of some of the 
metagraywacke rocks in other areas, further indi- 
cating sedimentary processes. 

A wide variety of rocks are present in the 
Carolina Slate Belt and various attempts have 
been made to divide them into units or forma- 
tions. Conley (1959) and Stromquist and Conley 
(1959) proposed a three fold division of the 
rocks of the Albemarle and Denton 15-minute 
quadrangles, while Conley and Bain (1965) pro- 
posed a set of nomenclature for the rock-strati- 
graphic units and their areal extent in the Caro- 
lina Slate Belt. Since these proposals are not well 
known and generally accepted and since the rocks 
of the Carolina Slate Belt fall into three natural 
divisions, it appears that these three natural divi- 
sions are to be preferred in this discussion. These 
three divisions are Felsic volcanic rocks, Mafic 
volcanic rocks and Bedded argillites (volcanic 


Felsic. volcanic rocks occupy about half of the 
Carolina Slate Belt in the central part of the 
State and are the predominating rocks in the 
eastern part of the Piedmont Plateau. In this area 
they occupy much of the Carolina Slate Belt 
west of the Durham and Deep River Triassic 
basins and northeast of Anson, Union and Stanly 

The felsic volcanic rocks consist largely of ma- 
terials of volcanic flow or fragmental origin. The 
flows are essentially rhyolite, while the frag- 
mental materials vary from rhyolitic to dacitic in 
composition. The fragmental rocks consist of 
breccias and coarse and fine tuffs, with coarse 
and fine tuffs making up the greater portion of 
the occurrences. Lenses of mafic volcanics and 
bedded slate of limited extent are also present. 

The fragmental rocks consist of fine and coarse 
tuffs and breccias. The coarse tuffs predominate 
and contain the fine tuffs and breccias as inter- 
bedded bands and lenses. The fragments compos- 
ing these rocks are angular to well rounded and 
vary in size from nearly a foot to a fraction of an 
inch in diameter. 

The fine tuff occurs interbedded with both the 
slate and coarse tuff and grades into each of them. 
It has no wide areal extent but occurs as narrow 
bands and lenses in the coarse tuffs. 

Microscopically the fine tuff shows a crypto- 
crystalline ground mass with fragments of quartz 
and feldspar (orthoclase, albite, oligoclase) as 
well as secondary minerals epidote, clinozoisite, 
chlorite and calcite. Iron oxides are sparingly 
present. Some sections show small rock frag- 
ments containing original flow structure while 
others exhibit a parallel arrangement of the par- 
ticles due to metamorphism. 

The coarse tuff varies from a massive to a 
highly schistose type of rock, that in places has 
been so slightly changed as to show some of its 
original characters. There is every gradation to 
a fine tuff on one hand and to a breccia on the 
other. The freshly broken rock proves to be made 
up of quartz and feldspar grains and rock frag- 
ments of less than one-half an inch in diameter 
set in a bluish or greenish-gray groundmass, the 
whole often resembling an arkose. 

In thin section the coarse tuff shows fragmental 
phenocrysts of quartz, orthoclase and acid plagio- 
clase with fragments of different kinds of rocks, 
some of which show definite flow structure, all 
embedded in a fine-grained groundmass. Kao- 
linite, epidote and calcite form secondary prod- 
ucts. Biotite and muscovite are rare. Grains of 
hematite and limonite as well as small particles 
of titanite and apatite are found in most sections. 

Flows of rhyolite occur as narrow bands and 
lenses in the tuff into which they appear to grade 
at places. This apparent gradation is possibly due 
to the fact that some material classed as silicified 

fine tuff may be partially devitrified rhyolite. The 
rhyolite is dense and indistinctly porphyritic, 
with a dark gray to bluish color, and in fresh 
fracture shows a greasy luster. Flow lines have 
developed in numerous places and are best seen on 
weathered surfaces, while amygdaloidal structure 
may be found in a number of outcrops. 

In thin section the rhyolite shows phenocrysts 
of plagioclase (chiefly oligoclase) orthoclase and 
quartz, named in the order of relative abundance. 
Kaolinite, epidote and chlorite have developed 
commonly from the weathering of the feldspars, 
and calcite is frequently found along fractures in 
the rocks. 

Acid volcanic breccia includes all felsic rocks 
that exhibit a fragmental character sufficiently 
well defined to attract attention in the hand speci- 
men, and in which the fragments are over one- 
half inch in diameter. The size of the fragments 
(observed) varies from one-half inch to several 
inches in diameter. These rocks consist partly of 
brecciated tuff and partly of brecciated rhyolite. 
When freshly broken the breccia often shows a 
greenish or mottled-gray color, produced by vari- 
ous colored fragments in a finer groundmass. In 
places the breccia has been strongly sheared and 
it nearly always shows some mashing and schis- 
tosity, but on the whole is more massive than the 
finer tuff rocks. 

Thin sections show little difference from the 
regular coarse tuffs. The fragments are chiefly 
of tuffaceous or rhyolitic character with occa- 
sional slate fragments. Phenocrysts of quartz, 
orthoclase and plagioclase (chiefly oligoclase) are 
abundant. The fragments of the brecciated rhyo- 
lite phase show a flow structure. In all phases of 
the breccia the groundmass is altered and kao- 
linized. Grains of iron oxide chiefly hematite are 
present, while the secondary minerals epidote and 
calcite and secondary quartz are plentiful. 


Mafic volcanic rocks are scattered throughout 
the northern two thirds of the Carolina Slate 
Belt, but are most abundant along the western 
side. The rocks of this unit consist of volcanic 
fragmental and flow materials. The fragmental 
materials are chiefly normal tuffs and breccias of 
andesitic composition, while the flows vary from 
andesite to basalt. 

The tuffs are generally andesitic in composi- 
tion. In places they are fine grained and lack the 

fragmental appearance. In such areas, one of 
which may be seen along U.S. Highway 64, for a 
mile west of Haw River in Chatham County, the 
rock strongly resembles a graywacke. The tuffs 
contain much epidote and often have a greenish 
color. Other colors vary from dark gray to nearly 
black. In addition to epidote, plagioclase, quartz 
and secondary calcite, iron oxides are present. 
The mafic fragmental rocks are not as strongly 
metamorphosed as the felsic fragmental rocks, 
but contain a cleavage that strikes northeast and 
dips northwest in the southern part of the area 
and to the southeast in the northern part. 

The mafic breccia is distinctly more basic than 
the felsic breccias and appears to be mainly ande- 
sitic in composition. It consists chiefly of brec- 
ciated tuffs and flows, but ranges all the way 
from a fine and highly mashed tuff to a massive 
coarse breccia with fragments up to several inches 
in diameter. It varies from a dark gray through a 
chlorite and epidote green color. 

In thin section this rock appears more uniform 
than in the hand specimen. Fragmental materials 
embedded in a feldspathic groundmass make up 
most of the rock. The following minerals are 
present: orthoclase, plagioclase (oligoclase and 
andesine) chlorite, epidote, zoisite, clinozoisite, 
quartz, calcite, iron oxides, kaolinite and sericite. 

The andesite and basalt occur as bands and 
lenses interbedded with the fragmentals. The 
andesite is dark green in color, usually massive 
or fine grained, but occasionally coarsely por- 
phyritic. A coarse porphyritic variety, with horn- 
blende crystals up to two inches long occurs in 
western Randolph County. The basalt is dark to 
nearly black and often amygdaloidal. Both the 
andesite and the basalt are characterized by the 
lack of a well defined cleavage. The minerals pres- 
ent include epidote, plagioclase, quartz, secondary 
calcite and iron oxides. Epidote is the most abun- 
dant mineral present, giving the rock its green 
color. The name greenstone is often used for this 


Bedded argillites (volcanic slate) commonly 
referred to as slate, bedded slate, or volcanic 
slate, occur in the southern part of the Carolina 
Slate Belt and extend as far north as the central 
part of Davidson and Randolph counties. A few 
small areas occur on the east side of the belt in 
Montgomery, Moore and Chatham counties. There 

are, also, some small areas east of the Jonesboro 
fault in Anson and Richmond counties. 

The bedded argillites (volcanic slate) consist 
chiefly of dark colored or bluish shales or slates, 
which are usually massive and thick bedded. How- 
ever, the beds occasionally show very finely 
marked bedding planes. Contacts between the 
slates and tuffs are usually gradational and often 
a single hand specimen will show gradation from 
a bedded slate to a fine-grained tuff. In composi- 
tion the bedded argillites vary from felsic tuffa- 
ceous argillite to mafic tuffaceous argillite inter- 
mixed with varying amounts of weathered 
material and land waste. Much of the slate is 
massive and jointed showing little effects of meta- 
morphism while in other places it has been 
strongly metamorphosed and shows a well defined 
slaty cleavage. The cleavage or schistosity does 
not in most places correspond to the bedding 
planes of the rock. In places, especially near 
igneous intrusives and mineralized zones, the slate 
is often highly silicified and resembles chert. 


The Carolina Slate Belt is bordered on the 
west by an igneous complex composed of gabbro, 
diorite and granite and intruded at many places, 
particularly in the northern half by granitic-type 
rocks. These igneous intrusives apparently vary 
from late Ordovician to early Permian in age. 


The occurrence of volcanic-sedimentary rocks 
along the western edge of the Coastal Plain and 
eastern edge of the Piedmont Plateau, in a long 
narrow belt that extends from southeastern Vir- 
ginia to central Georgia, with a length of more 
than 400 miles and width up to 120 miles, sug- 
gests deposition under geosynclinal conditions. 
As indicated above, these rocks consist of a great 
volcanic-sedimentary series varying from felsic 
to mafic in composition and composed of lava 
flows, beds of breccia, coarse tuff, fine tuff and 
ash, and feeds of shale or slate now designated as 
bedded slates or argillites. The lava flows and the 
coarse angular tuff and breccias could have been 
formed on land or under water. Conclusive evi- 
dence for one as opposed to the other is lacking. 
Many of the tuffs and breccias consist largely of 
subangular to rounded fragments that were cer- 
tainly reworked and deposited in water. The 

bedded slates and argillites were definitely water 
laid. Their composition, both chemical and physi- 
cal, and their texture indicate that they were not 
transported great distances. Finally, the presence 
of varying amounts of nonvolcanic materials or 
land waste in the form of mud, clay, silt, sand 
and at places rounded quartz pebbles up to an 
inch in diameter indicate that varying amounts of 
materials were brought into the area from ad- 
jacent land masses. 

There seems to be little doubt that the rocks of 
the Carolina Slate Belt were formed in a eugeo- 
syncline. The volcanic materials in this geosyn- 
cline came largely from beneath the surface by 
volcanic eruptions, while the nonvolcanic sedi- 
ments came from narrow belts of uplift that were 
present in or adjacent to the trough. 

The thickness of these rocks is variable but un- 
known. It appears possible, however, that in cen- 
tral North Carolina, west of the Durham, Deep 
River and Wadesboro Triassic basins, the vol- 
canic-sedimentary series may have a thickness up 
to 20,000 or 30,000 feet. The period of volcanic- 
activity during which this great series of volcanic- 
sedimentary rocks were being formed must have 
continued through a very long time, perhaps 
hundreds of thousands or even millions of years. 
During this time, there were innumerable alter- 
nations between quiet upwelling of lava, explo- 
sive activity piling up great amounts of tuff, 
breccia and ash and periods of comparative quiet 
accompanied by weathering, erosion and deposi- 
tion of the bedded deposits. Between successive 
outbursts the magma probably underwent some 
degree of differentiation so as to give rise to 
more acid rocks at one time and more basic at 
another. Such changes were not great for at no 
time did the products depart far from the general 
type which was a relative acid magma rich in 


The chief structural features of the rocks of 
the Carolina Slate Belt are cleavage planes, 
joints, folds and faults. The first of these to be 
of interest was the cleavage planes. Olmsted 
(1825) designated these rocks as the Great Slate 
Formation because of the well developed, slate- 
like cleavage which he observed over most of the 
area. In general, rocks of the Carolina Slate Belt 
south of U.S. Highway 70 from Durham to 
Greensboro have a well defined cleavage that 

strikes northeast and dips steeply to the north- 
west. North of this line the cleavage continues 
to strike northeast but much of the dip is to the 
southeast and at a lower angle than that which 
dips to the northwest. No explanation for this 
change in dip is readily available. 

The metamorphism which produced the cleav- 
age was not as intense as was originally thought 
and also varied widely from place to place. At 
places, metamorphism was so severe that the 
cleavage has become schistosity and the rocks are 
essentially schists. At other places, the cleavage 
apparently grades into jointing. As a result, the 
massive rocks are highly jointed and contain 
poorly developed cleavage planes. 

Recent work has revealed that folding is better 
developed than was formerly thought. It is now 
established that the rocks are in general well 
folded into a series of anticlines and synclines. 
The largest and most important fold is the Troy 
anticlinorium which trends in a northeast-south- 
west direction and whose axis lies a short dis- 
tance west of Troy. West and southwest of the 
Troy anticlinorium, northeast-trending open fold- 
ed synclines and anticlines predominate. The 
most important of these is the New London syn- 
cline. East, southeast, and northeast of the Troy 
anticlinorium the intensity of the folding in- 
creases. The rocks are tightly compressed into 
northeast-trending, asymmetric folds whose axial 
planes usually dip steeply to the northwest. 

The bedded argillites (volcanic slate) seem to 
have consolidated readily and folded like normal 
sediments while the tuffs and breccias remained 
in a state of open texture and tended to mash and 
shear instead of folding. This is indicated by the 
mashed and sheared condition of practically all 
the tuffs while in numerous cases more or less 
well preserved bedding planes in the slates indi- 
cate definite folding. 

Numerous insignificant faults occur in nearly 
all parts of the Carolina Slate Belt. These in gen- 
eral never amount to more than a few feet and 
are doubtless only the adjustments due to the 
folding of the rocks and are not of any great 
structural importance. However, along the east- 
ern border of the belt where the Carolina Slate 
Belt rocks have been compressed into northeast- 
trending asymmetric folds whose axial planes dip 
steeply to the northwest, thrust faults are present. 
The abundance and importance of these faults 
in relation to the overall structure of the Carolina 
Slate Belt are not yet fully established, but recent 

geologic mapping has revealed the presence of 
such faults in Moore and Orange counties. 


Emmons (1856), the first worker to date the 
rocks of the Carolina Slate Belt, considered them 
to be mainly slates and quartzites of sedimentary 
origin as shown by the presence of rounded peb- 
bles. He divided these rocks into a lower and 
upper series and placed them in his Taconic 
system which was early Paleozoic in age. He con- 
sidered the talcose slates of the lower series to 
have essentially the same composition as the 
underlying primary series and stated: "The tal- 
cose slates may be regarded as the bottom rocks, 
the oldest sediments which can be recognized, 
and in which, probably, no organic remains will 
be found." 

Later Emmons found near Troy, Montgomery 
County, two or three species of fossils in the 
lower series of the Taconic system. These fossils, 
which belonged to the class of zoophites, the low- 
est organisms of the animal kingdom, were found 
through about 1000 feet of rock and occurred 
from a few in number to abundant. 

The fossils were considered to be corals of a 
lenticular form that varied in size from a small 
pea to two inches in diameter. At first, Emmons 
considered the difference between the small and 
the larger forms to be the result of age but 
later decided that they were specific and named 
the small form Paleotrochis minor and the large 
form Paleotrochis major. 

These forms were of interest to Emmons main- 
ly in showing that lower Taconic rocks were fos- 
siliferous rather than in actually dating the rocks. 
Paleotrochis major and Paleotrochis minor were 
later identified as spherulites in rhyolite and not 
fossils, Diller (1899). 

Kerr (1875) classed the rocks of the Carolina 
Slate Belt as Huronian in age, which in his classi- 
fication is a division of the Archean. Williams 
(1894) classed them as Precambrian in age. Wat- 
son and Powell (1911) on the basis of fossils, 
considered the Arvonia slates of the Piedmont of 
Virginia to be Ordovician in age. Laney (1917) 
on the basis of the work by Watson and Powell, 
classed the volcanic-sedimentary rocks of the 
Virgilina district of the Carolina Slate Belt as 
Ordovician in age. 

In recent years the trend has been to place the 
age of these rocks as early Paleozoic, probably 

Ordovician. According to the U.S. Geological Sur- 
vey, Professional Paper 450A, Research 1962, 
"Lead-alpha measurements by T. W. Stern on 
zircon collected by A. A. Stromquist and A. M. 
White from felsic crystal tuffs in the Volcanic 
Slate belt of the central North Carolina piedmont 
have confirmed a previously inferred Ordovician 
age for these unfossiliferous rocks." White, et. al. 
(1963) gave the details on the collection and 
evaluation of two samples of zircon from the 
Albemarle quadrangle and stated: ". . . the indi- 
cated age for each is Ordovician according to 
Holmes time scale (Holmes, 1959, p. 204) ." 

Recently, St. Jean (1964) reported the first 
authentic discovery of fossils in the Carolina 
Slate Belt of North Carolina. The discovery con- 
sisted of two abraded and moderately distorted 
thoraxes and pygidia of a new trilobite species. 
The specimens were collected from a piece of 
stream rubble in Island Creek at Stanly County 
Road 1115. The type rock in which the fossils 
occurred is present in outcrops upstream. St. 
Jean classed the specimens as a new species ques- 
tionably assigned to the Middle Cambrian genus 
Paradoxides and stated: "Although the generic 
assignment is questionable, the morphologic char- 
acters of the two specimens indicate an age no 
younger than Middle Cambrian and no older than 
the age of the oldest known Early Cambrian tri- 

"The specimens are significant because they 
represent the first authentic fossil material from 
the Piedmont south of Virginia and provide 
paleontological documentation of the age and 
marine nature of a lithologic unit in the area. 
Micropygous Cambrian trilobites are more com- 
mon in eugeosynclinal belts, which part is in 
keeping with the paleogeographic and lithologic 

Granites of post-Ordovician but Paleozoic age 
and diabase dikes of Triassic age both intrude the 
Carolina Slate Belt rocks. The granites apparently 
furnished the solutions that produced the pyro- 
phyllite and associated minerals, and are con- 
sidered further below. The diabase dikes have 
no relations to the pyrophyllite deposits and are 
not discussed further. 



Just when pyrophyllite was first discovered in 
North Carolina is not known. Olmsted (1822) in 

a report entitled, "Descriptive Catalogue of Rocks 
and Minerals Collected in North Carolina" listed 
talc and soapstone from several counties includ- 
ing Chatham and Orange and stated that fhey 
were extensively used for building and orna- 
mental purposes, and added that Indian utensils 
of the same materials were common. In 1825 he 
called attention to the "Great Slate Formation" 
which passes across the State from northeast to 
southwest and again noted the presence of talc 
and soapstone in Chatham and Orange counties. 
Since no talc and soapstone are known to occur 
in rocks of the Carolina Slate Belt and since 
pyrophyllite is found at a number of localities in 
the belt it is quite probable that the deposits 
mentioned by Olmsted were pyrophyllite. 

Emmons (1856) described a material which 
was locally known as soapstone at Hancock's Mill, 
(Now Glendon) Moore County and near Troy, 
Montgomery as follows : "A rock, which occurs in 
extensive beds, and known in the localities where 
it is found as a soapstone, can by no means be 
placed properly with the magnesium minerals. It 
is white, slaty, or compact translucent, and has 
the common soapy feel of soapstone, and resem- 
bles it so closely to the eye and feel that it would 
pass in any market for this rock. It has, how- 
ever, a finer texture, and is somewhat harder; 
but it may be scratched by the nail, so that it 
ranks with softest of minerals: it scratches talc, 
and is not itself scratched by it; it is infusible 
before the blowpipe, and with nitrate of cobalt 
gives an intensely blue color, proving thereby the 
presence of alumina in place of magnesia." He 
classed the mineral as agalmatolite, the figure 
stone of the Chinese, and described the methods 
used in quarrying it at Hancock's Mill. 

Brush (1862) analyzed some of the material 
from Hancock's Mill, Moore County and showed 
it to be pyrophyllite. 

Pratt (1900) described the deposits and pub- 
lished further analyses of the pyrophyllite. He 
stated that : "While the talc deposits of Cherokee 
and Swain counties are pockety in nature and of 
limited depth, the pyrophyllite formation is con- 
tinuous and of considerable, though of unknown 

Pratt described the pyrophyllite as follows: 
"While possessing many of the physical proper- 
ties of talc and often being mistaken for it, the 
pyrophyllite is quite different in its chemical com- 
position, and is a distant mineral species. Al- 
though this mineral probably cannot be put to 

all the uses of talc, it can be used for the larger 
number of them, and those for which the talc is 
used in the greatest quantity. Some of this might 
be of such quality that it could be cut into pencils, 
but the most of this mineral would only be of 
value when ground. It is soft with a greasy feel 
and pearly luster, and has a foliated structure. 
The color varies from green, greenish and yel- 
lowish-white to almost white; but when air-dried 
they all become nearly white. Very little compact 
pyrophyllite has been observed that would be 
suitable for carving, as is used in China, although 
considerable of this has been used in the manu- 
facture of slate pencils." 

Pratt presented three chemical analyses of 
pyrophyllite from Moore County that were very 
close to the theoretical composition of that min- 
eral. He, also, pointed out that the deposits had 
been worked almost continuously since the Civil 

Hafer (1913) noted that the pyrophyllite did 
not differ greatly from the sericite found in the 
old gold mines of the slate belt and may have 
originated in the same manner. He, also, called 
attention to the masses of pyrite-bearing quartz 
that are often found associated with the pyro- 
phyllite deposits. 

Stuckey (1928) presented the first detailed re- 
port of the pyrophyllite deposits of North Caro- 
lina. He described their distribution, geological 
setting, form or shape, mineralogy, origin and 
possible continuation with depth. He classed the 
deposits as hydrothermal in origin and thought 
that they might continue to considerable depths. 


Pyrophyllite occurrences are known along the 
eastern half of the Carolina Slate Belt from the 
vicinity of Wadesville in the southwestern part 
of Montgomery County northeastward to the 
northern part of Granville County near the Vir- 
ginia line. These occurrences may consist of a 
single deposit or they may contain several pros- 
pects or deposits. 

In Montgomery County pyrophyllite is known 
to occur near Wadesville ; on Cotton Stone Moun- 
tain, 3.5 miles north of Troy; just east of State 
Road 1312 near Abner; and northeast of Asbury 
in the northeastern corner of the county. Consid- 
erable prospecting has been done near Wadesville 
and the area appears promising for mining. 
Limited prospecting has been done on Cotton 

Stone Mountain but no mining has been carried 
out. Limited prospecting and some mining have 
been carried out on the deposit near Abner but 
the property is currently idle. One deposit north- 
east of Asbury appears to have been worked out, 
but another is promising for future development. 

In Moore County, pyrophyllite is found ap- 
proximately four miles southwest of Spies near 
the point where Cotton Creek enters Cabin Creek ; 
near Robbins; and in a zone several miles long 
that lies along Deep River north of Glendon. The 
Robbins area contains the only underground 
mine, which is the largest pyrophyllite mine in 
the State, and several open pit prospects. The 
Glendon zone contains three active open cut mines 
and a number of prospects. 

Pyrophyllite is known to occur in Randolph 
County in the vicinity of Pilot Mountain about 8 
miles southeast of Asheboro, just north of State 
Highway 902, and near Staley in the northeastern 
part of the county. In the Pilot Mountain area 
there are four prospects, one of which has been 
explored and considerable iron-stained pyrophyl- 
lite is reported to be present. No mining has been 
carried out in this area. The deposit near Staley, 
which at one time contained the second largest 
mine in the State, has been worked out and aban- 

The only known pyrophyllite area in Chatham 
County is located near the Chatham-Alamance 
county line on the Hinshaw property. This prop- 
erty is about 2 miles east of State Road 1004 and 
a short distance north of State Road 1343. Pyro- 
phyllite crops out at three places in the area, one 
of which has been prospected to a limited extent. 
No mining is being carried out in the area. 

Pyrophyllite is known to occur at two localities 
near Snow Camp in southern Alamance County. 
On Pine Mountain southeast of Snow Camp is a 
major open pit mine from which pyrophyllite 
has been mined for more than 20 years. About 2 
miles east of Snow Camp there are several pyro- 
phyllite exposures on a prominent hill known as 
Major Hill. Major Hill lies south of State Road 
1005 and between State Roads 2356 and 2351. 
The outcrops in Major Hill are promising and 
prospecting is currently underway. 

In Orange County pyrophyllite is known to 
occur in the vicinity of Teer in the southwestern 
part of the county; near Hillsborough; and on 
the Murray estate about 6 miles northeast of 
of Hillsborough. In the vicinity of Teer, prospect- 
ing has been carried out at three or more places 


and limited mining was done at one time. This 
area has been abandoned at least temporarily. 
South and southwest of Hillsborough are three 
prominent hills which trend northeast and parallel 
the major geologic structure of the area. The 
northern most of these hills contains a major open 
cut pyrophyllite mine that is an important pro- 
ducer of pyrophyllite, andalusite, sericite and 
silica. The deposit in the Murray property north- 
east of Hillsborough lies south of State Road 1538 
and west of State Road 1548. Considerable pro- 
specting has been carried out on this property, 
but no mining has been done. 

In Granville County, pyrophyllite deposits are 
found on Bowlings Mountain northwest of Stem ; 
at several places on Long Mountain which lies to 
the northwest of Bowlings Mountain; and on 
Daniels Mountain about 9 miles north of Oxford. 
On Bowlings Mountain, which is located about 
three miles slightly northwest of Stem, prospect- 
ing and some mining have exposed a major pyro- 
phyllite deposit. To the northwest of Bowlings 
Mountain is a northeast trending series of irregu- 
lar hills that occupy an area a mile or more in 
width and some 4 miles long, known as Long 
Mountain. Prospecting and some exploration have 
demonstrated the presence of pyrophyllite at sev- 
eral places on Long Mountain, but no mining has 
been done. About 9 miles north of Oxford and 1.5 
miles northeast of State Highway 96 and east of 
Mountain Creek is Daniels Mountain on which 
pyrophyllite is known to occur. No prospecting or 
mining has been done on this mountain. 


All the pyrophyllite deposits of North Carolina 
occur in acid volcanic rocks, chiefly in medium 
to fine-grained tuffs and to a less extent in an 
acid volcanic breccia. They are not found at any 
place in a basic andesitic type of rock or asso- 
ciated with a typical water-laid slate. At the 
Phillips, Womble and Reaves mines, which are 
found in the Deep River pyrophyllite zone north 
of Glendon, Moore County, the footwall side of 
the pyrophyllite bodies is an acid volcanic breccia. 
Next to the footwall is a highly mineralized pyro- 
phyllite zone that grades into a fine-grained acid 
tuff. At places the pyrophyllite grades into and 
replaces parts of the brecciated footwall. Where 
the band of volcanic breccia is absent from the 
footwall side of the deposits, in this zone, the 

pyrophyllite bodies are much nearer the slate 
than where the breccia is present, but they are 
never found in normal slate. On the hanging wall 
side the pyrophyllite grades into medium to fine- 
grained acid tuff. 

The geologic distribution of the pyrophyllite 
deposits is probably controlled in part by the 
composition of the rocks and in part by rock 
structures. As indicated above (page 8), the 
tuffs and breccias remained in a state of open 
texture and tended to mash and shear instead of 
folding. As a result, the acid tuffs and breccias 
developed shear zones along which the pyrophyl- 
lite mineralization was later concentrated. A few 
shear zones, particularly those along Deep River 
near Glendon and near Robbins (both in Moore 
County) were developed along major thrust 
faults. However, the great majority of the pyro- 
phyllite deposits are found in shear zones that 
do not show any evidence of containing faults. 


A prominent feature of the pyrophyllite bodies 
is their irregular, oval, or lens-like form. This 
structure is observed along the strike and also 
vertically to the depths reached in mining. In 
nearly every deposit that has been developed 
enough to show the true structure, bodies and 
lenses of pyrophyllite are found along with lenses 
of tuffaceous rocks that exhibit various stages of 
alteration. Most pyrophyllite deposits occur as 
narrow bands or zones aligned with the cleavage 
strike and dip of the country rock. They range 
in size from those measured in inches up to 500 
feet wide and 1500 to 2000 feet long. The strike 
of the cleavage in both the country rock and the 
pyrophyllite bodies is northeast-southwest, while 
the dip is steeply to the northwest. 

In most cases the larger mineralized zones con- 
sist of a very siliceous footwall, a well developed 
mineralized zone and a highly siliceous and seri- 
citic hanging wall. Where these conditions exist 
contacts between the mineralized zone and the 
footwall and the hanging wall are gradational. 
Contacts between the footwall and country rock 
and the hanging wall and country rocks are, also, 
gradational. When the siliceous footwall and the 
sericitic hanging wall are absent, as they fre- 
quently are, contacts between the mineralized 
zones and the country rocks are gradational. 

Excellent examples of the siliceous footwall 
may be seen at the Bowlings Mountain deposit, 


Granville County, at the Hillsborough deposit, 
Orange County, at the Staley deposit, Randolph 
County, and at the mine of the Standard Mineral 
Company, Moore County. In general, it consists 
of a light blue-gray to white, fine-grained to 
medium-grained rock having the general appear- 
ance of quartzite. Selected samples from the more 
massive portions of this rock consist almost en- 
tirely of silica. The rock has been fractured con- 
siderably at places and contains varying amounts 
of sericite and pyrophyllite. When fresh, the rock 
is hard and dense and breaks with a conchoidal 
fracture. When weathered, it breaks down to a 
sandy friable material that is usually white, but 
is often stained various shades of yellow and red 
by iron oxide. 

The siliceous footwall ranges from less than 5 
to more than 50 feet in thickness and in many 
cases extends the entire length of the deposit. 
When it occurs as a massive unit, it often crops 
out as bold ledges near the crest of the hill as at 
the Staley and Hillsborough deposits. However, 
as at the mine of the Standard Mineral Company 
near Robbins, Moore County, it may not crop out 
at all. From the footwall mineralization increases 
inward to rich zones and lenses of pyrophyllite 
and then decreases towards a schistose and seri- 
citized hanging wall. 


The minerals most commonly observed in the 
pyrophyllite deposits in the apparent order of 
their abundance are pyrophyllite, quartz, sericite, 
chloritoid, pyrite, chlorite, feldspar, iron oxides, 
zircon, titanite, zeolites and apatite. Of these, 
only the first eight are present in important 
amounts or related to the development of the 
pyrophyllite. The other minerals are present in 
small amounts to the extent they might occur as 
accessory constituents of an igneous rock or as 
products of regional metamorphism or weather- 

In addition, small amounts of fluorite have 
been found with quartz veins intruding the fault 
zone at the Phillips mine. Also, varying amounts 
of the high-alumina minerals andalusite, dia- 
spore, kyanite and topaz have been found in sev- 
eral pyrophyllite mines and prospects. The posi- 
tion of these high-alumina minerals in the 
mineral sequence of the pyrophyllite deposits is 
not clear and they are discussed below. 


Pyrophyllite is a hydrous aluminum silicate 
with the general formula H 2 Al2Si 4 0i2. It crystal- 
lizes in the orthorhombic system, but good crys- 
tals are rare. It commonly occurs as (1) foliated, 
(2) granular and (3) radial or stellate masses. 
The color varies from nearly black through yel- 
lowish white, green, and apple green to pure 
white. It has a specific gravity of about 2.8 to 2.9, 
and a hardness less than the finger nail. It has a 
pearly luster, a greasy feel and commonly occurs 
as masses, lenses and pockets associated with 
quartz, sericite and chloritoid. The pyrophyllite in 
the deposits near Glendon and Robbins, Moore 
County, consists almost entirely of the foliated 
variety. That in the other major deposits consists 
largely of massive granular and radial fibrous 
forms with occasional small amounts of the foli- 
ated variety. 


Quartz is an oxide of silicon with the general 
formula Si0 2 . It crystallizes in the hexagonal 
system, and good crystal specimens are common. 
Quartz is colorless when pure, has a conchoidal 
fracture, a viterous luster, a hardness of 7 and 
a specific gravity of 2.65. It is abundant through- 
out the deposits everywhere except in the very 
purest pyrophyllite and occurs (1) as large 
masses of cherty or milky appearance, (2) as 
clear veins and stringers in the deposits and 
along the walls, and (3) as small masses and 
nodules in the altered or only partly altered rock. 


Sericite is a fine-grained variety of mica, usual- 
ly muscovite, occurring in small scales and having 
the composition (H,K)AlSi0 4 . It crystallizes in 
the monoclinic system, has a basal cleavage, a 
hardness of 2-2.25, a specific gravity of 2.76-3 
and a vitreous luster. The color varies from color- 
less through gray, pale green, and violet to rose- 
red. Sericite is often concentrated as bands or 
zones along the hanging wall of the pyrophyllite 
bodies and to a lesser extent along the footwall. 
It is, also, present as finely divided scales and 
flakes and as zones through good pyrophyllite. 


Chloritoid probably crystallizes in the triclinic 
system but rarely occurs in distinct tabular crys- 


tals. It often occurs in the form of sheaves or 
rosettes. The general formula is H 2 (Fe,Mg) 
Al 2 Si0 7 . It has a basal cleavage, a pearly luster, 
a hardness of 6.5 and a specific gravity of 3.52- 
3.57. The color varies from dark gray through 
greenish black to grayish black. Chloritoid is 
found in varying amounts in all the pyrophyllite 
deposits but is most abundant in those along 
Deep River north of Glendon, Moore County 
where an acid iron breccia forms part of the 


Pyrite has the formula FeS 2 , crystallizes in the 
isometric system and often occurs as good crys- 
tals. It has a conchoidal fracture, a hardness of 
6-6.5, a specific gravity of 4.95-5.10, a metallic 
luster and a brass-yellow color. It is present in 
small amounts associated with the silicified tuff 
along the walls of the pyrophyllite bodies and in 
the lenses of silicified country rock included in 
the deposits. 


Chlorite, probably clinochlore, has the formula 
H 8 Mg5Al2Si 3 18 , crystallizes in the monoclinic sys- 
tem and usually occurs as flakes or scales. It has 
a hardness of 2-2.5, a specific gravity of 2.65-2.78, 
a pearly luster, and a grass-green to olive color. 
Chlorite occurs rather commonly in the impure 
portions of the pyrophyllite bodies and in the 
altered wall rocks. 


Feldspars, orthoclase (KAlSi 3 8 ), albite 
(NaAlSi 3 8 ), and in one case andesine, a mixture 
of albite (NaAlSi 3 8 ) and anorthite 
(CaAl 2 Si 2 9 ), were found in small amounts in 
the less silicified portions of the wall rock of the 
pyrophyllite bodies. Orthoclase and albite are 
more abundant due to the fact that they are com- 
mon constituents of the rhyolitic and dacitic rocks 
in which the pyrophyllite was formed. 

Iron Oxides 

Iron oxides, chiefly hematite Fe 2 3 and magne- 
tite Fe 3 4 , occur in small amounts in each pyro- 
phyllite deposit studied, but most abundantly in 
the footwall of the mines along Deep River north 

of Glendon, Moore County, where an acid iron 
breccia is present. 

High Alumina Minerals 

One or more of the high-alumina minerals an- 
dalusite (Al 2 Si0 5 ), diaspore (A1 2 3 H 2 0), kyanite 
(Al 2 Si0 5 ) and topaz (AlF) 2 Si0 4 , are present in 
varying amounts in most of the pyrophyllite de- 
posits except those in Moore County, and Conley 
(1962a) reported collecting a specimen from the 
fault zone in the Phillips mine that contained 
pyrophyllite, diaspore, topaz and fluorite. 

The occurrence of high-alumina minerals in the 
pyrophyllite deposits is quite irregular, with the 
greatest concentrations near the footwall and 
lesser amounts along the hanging wall and asso- 
ciated with lenses of only partly altered country 
rock included in the deposits. Andalusite is abun- 
dant in the Hillsborough deposits. In the deposit 
on Bowlings Mountain, Granville County, there 
is considerable topaz as well as small amounts of 
andalusite and kyanite. Some blocks of topaz are 
in the pyrophyllite deposits today and represent 
material that was not replaced or destroyed dur- 
ing pyrophyllite formation. 


A careful study of a number of thin sections 
cut from specimens collected at the various mines 
and quarries shows that the pyrophyllite deposits 
have been formed in volcanic tuffs and to some 
extent in a volcanic breccia that varied from 
dacitic to rhyolitic in composition. 

Sections from specimens of tuff and breccia col- 
lected along the walls of the pyrophyllite bodies 
and from partly altered country rock included in 
them show that the minerals of the pyrophyllite 
bodies were formed in the order of quartz, pyrite, 
chloritoid, sericite, and pyrophyllite; and that 
these minerals have definite relations to each 
other and to the feldspars and iron oxides in the 
country rock. 

The first change was a marked silicification of 
the enclosing rocks accompanied by a rapid de- 
crease in their normal mineral content. The feld- 
spars, rock fragments, and fine-grained ground- 
mass of the rocks were readily replaced by quartz 
to the extent that the altered rocks became masses 
of cherty and milky quartz. 

At the Womble and Phillips mines north of 
Glendon, Moore County and at the Staley mine 3 


miles west of Staley, Randolph County, the silici- 
fication was accompanied or immediately followed 
by the development of pyrite, as this mineral is 
found in the silicified wall rocks of the mines and 
in included masses of silicified country rock but 
not in good pyrophyllite. 

Chloritoid is found in varying amounts at all 
the prophyllite prospects and mines but is more 
abundant at some including the Womble and 
Phillips mines north of Glendon, Moore County 
and the Murray prospect 5 miles northeast of 
Hillsborough, Orange County and the Staley mine 
3 miles west of Staley, Randolph County. At the 
Womble and Phillips mines it is apparently re- 
lated to an acid iron breccia which contains con- 
siderable magnetite and hematite and forms the 
football of these deposits. The chloritoid at the 
Murray prospect and the Staley mine seems to 
be related to bands and zones of greenstone in 
the wall rocks of the bodies near the pyrophyllite. 

The chloritoid was not observed replacing the 
iron oxides but the marked increase and close 
association of chloritoid with the iron oxides at 
every point where the latter are present suggests 
a close genetic relation between the two. The 
chloritoid was developed along with or soon after 
the silicification of the tuff and in thin sections 
is seen to have partly replaced the quartz. 

Sericite is often concentrated as bands or zones 
along the hanging wall of the pyrophyllite bodies 
and to a lesser extent along the footwall. It is 
also present as finely divided flakes and scales 
and as zones through good pyrophyllite. Thin sec- 
tions cut from silicified and partly prophyllitized 
masses from the various pyrophyllite deposits 
show sericite associated with pyrophyllite and 
having about the same relations to the quartz. 
The cherty or flinty masses of quartz in the pyro- 
phyllite bodies are cracked and shattered and 
partly replaced by sericite. 

The microscope shows pyrophyllite to be the 
last mineral formed. In every case silicification 
preceded the development of pyrophyllite. 

The feldspars diminish with silicification so 
that feldspar and pyrophyllite are seldom found 
in the same section. Where pyrophyllite is found 
in sections with chloritoid, it occurs in every 
crack and opening in the sheaves and bundles of 
chloritoid as a replacement of the chloritoid. Prac- 
tically all specimens except those from the purest 
pyrophyllite, contain some quartz, the amount of 
the latter depending upon the purity of the speci- 

men in terms of pyrophyllite. In sections from 
such specimens the pyrophyllite is replacing the 
quartz. Sections from the masses of cherty or 
milky quartz associated with pyrophyllite show 
both sericite and pyrophyllite replacing the quartz 
with sericite apparently earlier than the pyro- 
phyllite. The position of the minerals andalusite, 
diaspore, kyanite and topaz in the sequence is not 
clear, but they appear to have been formed before 
or early in the pyrophyllitization process as they 
have been replaced partially by sericite and pyro- 


In considering the origin of the pyrophyllite 
deposits, it has been necessary to take into ac- 
count their shape and distribution, their relations 
to the enclosing rocks, their mineralogical com- 
position, the relations of the associated minerals 
to each other, and the relations of the pyrophyl- 
lite to the associated minerals and the enclosing 
rocks. Over the years, ideas as to the origin of 
pyrophyllite have changed and future develop- 
ment of the deposits may disclose new informa- 
tion that may require new explanations. This is 
especially true since the deposits are associated 
with metamorphic rocks and ideas on the origin 
of metamorphic rocks and their contained miner- 
als are in a state of change. 


Before discussing the origin of North Carolina 
pyrophyllite, reference should be made to the 
views expressed by other writers on the origin of 
this mineral and the chloritoid and sericite asso- 
ciated with it. 

Emmons (1856) considered pyrophyllite (agal- 
matolite) as a sedimentary rock near the base of 
his Taconic system. Levy and Lacroix (1888) 
stated that pyrophyllite occurs in metamorphic 
rocks while Dana (1909) classed it as a mineral 
formed at the base of schists or as a mineral of 
the crystalline schists and Paleozoic metamor- 

Clapp (1914) described pyrophyllite deposits 
on the west side of Vancouver Island, British 
Columbia. Both alunite and pyrophyllite occur 
in andesite, dacite and associated pyroclastic 
rocks. This series and in particular its fragmental 
parts, has been metasomatically altered to quartz- 
sericite-chlorite rocks, quartz-sericite rocks, 


quartz-pyrophyllite rocks and quartz-alunite 
rocks. Clapp concluded that most of the minerali- 
zation was caused by hot sulphuric acid solutions 
of volcanic origin which were active during the 
accumulation of the pyroclastic rocks, and as a 
result of relatively shallow depths and low pres- 
sures. He postulated little change in the bulk 
composition of the original volcanic rocks and 
interpreted most of the new minerals as having 
been developed from feldspars. In general, how- 
ever, the quartz-pyrophyllite rocks show a net 
gain in alumina, a loss of potash and either a loss 
or a gain in silica. 

Buddington (1916) and Vhay (1937) have 
described in detail the pyrophyllite deposits in 
the Conception Bay Region of Newfoundland. 
These deposits occur in a thick series of Pre- 
cambrian rhyolite and basalt flows which contain 
interlayered breccias, tuffs and some waterlaid 
materials. These volcanic rocks were altered re- 
gionally with the development of abundant chlo- 
rite and silica. Locally, some of the rocks were 
pyrophyllitized, some pinitized and some silici- 

Some of the pyrophyllite concentrations are 
found in rhyolite breccias and conglomerates, but 
most are limited to the rhyolite flows. The pyro- 
phyllite itself forms single, well defined veins, as 
well as series of inter-connecting veins, lenses 
and pockets. The development of the pyrophyllite 
evidently involved the introduction of large 
amounts of alumina, the replacement of alkalies 
by hydroxyl, and the removal of silica, both that 
occurring as free quartz and that in the other 
minerals. Much of the pyrophyllitized rock may 
once have been a relatively homogeneous glass. 

Buddington (1916) concluded that these de- 
posits were formed by the metasomatic replace- 
ment of previously silicified rhyolites by thermal 
waters under conditions involving dynamic stress 
and intermediate temperatures and pressures. 
The solutions evidently moved along fault or shear 
zones, and the deposits have a marked schistosity. 
Vhay (1937) concluded that the individual flakes 
of pyrophyllite have a random orientation and 
that the schistosity of the deposits represent an 
inherited feature preserved by differential re- 
placement along schistose structures already 

The pyrophyllite deposits in the San Dieguito 
area of San Diego County, California, have been 
described in detail by Jahns and Lance (1950). 

These deposits were formed by the alteration of 
volcanic flows, breccias and tuffs that ranged in 
composition from andesite to rhyolite. 

Jahns and Lance (1950) described the origin 
of these deposits as follows : "The mode of occur- 
rence of the San Dieguito pyrophyllite, particu- 
larly its distribution with respect to fractures 
and shear zones in the host volcanic rocks, indi- 
cates that it was formed by replacement of these 
rocks. Its development was accompanied by intro- 
duction of Si0 2 , A1 2 3 and probably OH. The 
phyrophyllite bearing rocks, including those of 
highest grade, contain fresh pyrite and other sul- 
fide minerals at depths in excess of 20 feet in 
most parts of the area. Both pyrophyllite and 
sulfides appear to be hypogene, and are plainly 
earlier than the widespread iron oxides, man- 
ganese oxides and clay minerals of supergene 

"Under the microscope both pyrophyllite and 
quartz replace feldspars and other original min- 
erals of the volcanic rocks, and in many places 
the two replacing minerals are of the same gen- 
eral age. As pointed out by Bastin and others, 
(1931) aggregate, rather than sequential replace- 
ment, is characteristic of hypogene processes. 
Zonal distribution of replacing minerals with 
respect to remnants of earlier minerals, a feature 
so common in supergene replacement, is con- 
spiciously absent from the pyrophyllite-bearing 
rocks. Moreover, the replacement is not particu- 
larly selective; the pyrophyllite, although first 
attacking parts of the groundmass in the volcanic 
rocks is generally distributed throughout the 
phenocrysts and groundmass minerals." 

They conclude : "The metamorphism of the vol- 
canic rocks in the San Dieguito area, and the 
subsequent introduction of silica and pyrophyl- 
lite almost certainly took place during late Trias- 
sic or Cretaceous time. A considerable thickness 
of volcanic rocks was removed by erosion prior 
to deposition of the latest Cretaceous sediments 
in the region, so that it is impossible to establish 
a maximum depth at which the pyrophyllite de- 
posits were formed. At no place is the total thick- 
ness of the Santiago Peak volcanics known, but it 
may well have amounted to several thousand feet. 
On the basis of the general geologic relations and 
the indirect evidence from laboratory investiga- 
tions, it seems likely that the San Dieguito pyro- 
phyllite deposits were formed hydrothermally 
under conditions of intermediate temperatures 


and pressures. This is in accord with conclusions 
reached by Buddington (1916) for somewhat 
similar deposits in the Conception Bay region of 
Newfoundland, and by Stuckey (1925) for the 
deposits in the Deep River region of North Caro- 
lina. In contrast, the deposits on Vancouver Is- 
land, British Columbia, appear to have been 
formed under near surface conditions." 

Based on a study of samples collected from 
various pyrophyllite deposits of North Carolina, 
Zen (1961) tended to disregard the effect of 
hydrothermal replacement solutions on the forma- 
tion of the pyrophyllite bodies. He considered the 
presence of the three phase mineral assemblage 
of the ternary system A1 2 3 — H 2 — Si0 2 to 
indicate that water acted as a fixed component. 
He further noted, however, that to say water 
acted as a fixed component did not completely 
imply the absence of a free solution phase (hy- 
drothermal solutions). Such a phase could have 
existed, but certainly did not circulate freely 
through the system destroying the buffering 
mineral assemblages. 

Conley (1962a) concluded: "The bulk chemical 
composition of the pyrophyllite deposits is essen- 
tially the same as that of the country rock. All 
of the chemical elements present in the pyrophyl- 
lite deposits are present in the country rock, with 
the exception of fluorine, copper and gold. These 
elements are associated with quartz veins and 
silicified zones and were obviously brought in 
from an outside source. The pyrophyllite deposits 
could have formed in place with either addition 
or substraction of chemical elements if the ele- 
ments were properly segregated and recrystallized 
into new minerals." 

LeChatelier (1887) determined the tempera- 
ture at which pyrophyllite loses its water and 
found two points of marked loss, one at 700° and 
the other at 850° C. Stuckey (1924) made a com- 
parative dehydration test of pyrophyllite and 
sericite and found that sericite lost its water much 
faster than pyrophyllite at lower temperatures 
and at 750° C was practically dehydrated while 
the pyrophyllite held about 1 percent of its water 
which was finally lost at approximately 900° C. 

Rogers (1916) classed sericite as a typically 
low temperature mineral associated with the last 
stages of hydrothermal alteration while Lindgren 
(1919) classed it as a mineral common to hydro- 
thermal alterations at shallow and intermediate 
depths and pointed out that in acid rocks of the 

rhyolitic type silicification and sericitization are 
common near the surface, but did not agree with 
Rogers that sericite is a late mineral. 

While much has been published regarding the 
nature of chloritoid there is little definite infor- 
mation on its genesis. Clark (1920) stated that 
chloritoid is formed in schists where much iron 
and water are present, and that it is intermediate 
between the micas and chlorite and may alter 
into either. Manasse (1910) described a schist of 
sericite, quartz, rutile, tourmaline, chlorite and 
epidote from the Alps of Italy, closely associated 
with and occurring on both sides of a marble, in 
which chloritoid is abundant. 

Niggli (1912) in a study of the chloritoid and 
ottrelite groups of the Swiss Alps decided that 
the two minerals are identical. He pointed out 
that chloritoid is abundantly developed in schists 
that were originally high in clay content and 
thought that its formation was directly due to 
pressure and relatively independent of tempera- 
ture. He gave a diagram showing that regardless 
of temperature, chloritoid is formed with an in- 
crease in pressure and conversely it drops out 
when the pressure diminishes. 


In Table 1, on page 17, there are a number of 
chemical analyses of rocks and minerals from the 
Carolina Slate Belt of North Carolina and for 
comparison, several analyses of similar rocks 
from other regions. Number 1 is a rhyolite from 
Flat Swamp Mountain in the Carolina Slate Belt 
of Davidson County, North Carolina, while Num- 
ber 2 is a devitrified rhyolite from South Moun- 
tain, Pennsylvania. Number 3 is an average of 
115 analyses of rhyodacite and rhyodacite- 
obsidian obtained from widespread areas. Num- 
ber 4 is dacite from Kemp Mountain in the 
Carolina Slate Belt of Davidson County, North 
Carolina. Number 5, is dacite tuff, 1 mile south- 
east of Monteith Bay, Vancouver Island, while 
Number 6, is the same type of rock a short dis- 
tance away that has been silicified and altered 
to a cherty quartz-sericite rock. Numbers 7, 8, 
9 and 10, represent commercial pyrophyllite from 
4 mines in North Carolina. 

Analyses Number 1 through 5, Table 1, page 17, 
represent normal or average rhyolite and dacite 
rock types, and as is to be expected the bulk com- 
position of these analyses is remarkably uniform. 
Si0 2 varies from 66.27 to 74.67 percent, A1 2 3 


from 10.78 to 15.39 percent, CaO from 0.34 to 
3.68 percent, Na 2 from 3.40 to 5.46 percent, K 2 
from 1.74 to 3.01 percent, and H 2 from a trace 
to 0.68 percent. Analyses number 7 through 10, 
represent average commercial pyrophyllite, and 
as might be expected the bulk composition of 
these analyses is remarkably uniform. Si0 2 varies 
from 57.58 to 64.68 percent, A1 2 3 from 28.34 to 
33.31 percent, CaO from a trace to 0.72 percent, 
Na 2 from 0.06 to 0.38 percent, K 2 from a trace 
to 3.90 percent, and H 2 from 5.40 to 5.86 per- 

This change in bulk composition from rhyolite 
and dacite to pyrophyllite was brought about by 
silicification of the rhyolite and dacite to a cherty 
quartz rock as shown in analysis number 6, fol- 
lowed by replacement to pyrophyllite. As silicifi- 
cation advanced there was a decrease in alumina 

and alkalies and an increase in silica. Replace- 
ment by pyrophyllite, in some cases, preceded or 
accompanied by sericite, resulted in a decrease in 
silica and an increase in alumina, potash increas- 
ing with the sericite content, while water in- 
creased from about 1 percent to an average of 
5.59 percent. 

The conditions indicated by the above analyses 
may be observed at many of the pyrophyllite de- 
posits in the area. Beginning in walls of unaltered 
rhyolitic or dacitic tuff there is a gradual transi- 
tion through silicification, sericitization and pyro- 
phyllitization to lenses and masses of practically 
pure pyrophyllite in the interior of the bodies. 
As a result, the mineral bodies contain walls of 
silicified country rock that on the interior por- 
tions have been more or less sericitized and par- 
tially to completely pyrophyllitized. 

Table 1. Analysis of Rhyolite, Dacite and Pyrophyllite 











Si0 2 











A1 2 3 











Fe 2 3 








































Na 2 











K 2 











H 2 










C0 2 















1. Rhyolite from Flat Swamp Mountain, North Carolina, Pogue (1910) p. 54 

2. Devitrified rhyolite from South Mountain, Pennsylvania, Williams (1892) p. 494 

3. Average of 115 analyses of rhyodacite and rhyodacite-obsidian, Nockolds (1954) p. 1014 

4. Dacite from Kemp Mountain, Davidson County, North Carolina, Pogue (1910) p. 57 

5. Dacite tuff 1 mile southeast of Monteith Bay, Clapp (1914) p. 120 

6. Silicified dacite tuff (cherty quartz-sericite rock) Monteith Claim, Clapp (1914) p. 120 

7. Pyrophyllite from Rogers Creek Mining Company's mine, Pratt (1900), p. 26 

8. Pyrophyllite from Standard Mineral Company's mine, Stuckey (1928), p. 36 

9. Pyrophyllite from Womble mine, Stuckey (1928) p. 36 

10. Pyrophyllite from Gerhard Bros., Staley, North Carolina, Stuckey (1928) p. 36 



The field, microscopic and chemical evidence 
indicates that the pyrophyllite deposits in North 
Carolina have been formed through the metaso- 
matic replacement of acid tuffs and breccias of 
both rhyolitic and dacitic composition. The de- 
velopment of pyrophyllite was accompanied by 
the introduction of Si0 2 , A1 2 3 and water. The 
quartz, pyrite, chloritoid, sericite and pyrophyl- 
lite in the mineralized bodies are apparently of 
hypogene origin. 

Evidences that the deposits have been formed 
by replacement are as follows : 

(1) Gradational contacts between pure pyrophyllite 
and the unaltered country rocks. 

(2) The preservation of structures of the primary rocks 
in the mineralized rocks, such as bedding planes 
of the finer tuffs, and fragmental outlines of the 
coarser tuffs and breccias. 

(3) The presence of masses and lenses of practically 
pure or only partly altered country rock, appar- 
ently unattached and completely surrounded in the 
mineral bodies. 

(4) The introduction of some elements and the removal 
of others. 

(5) The lack of any noticeable change in the volume 
of the original rocks during the mineralization 

(6) The massive and homogeneous structure of the py- 

The following sequence of events is deduced : 

(1) The metamorphism of the volcanic fragmental and 
flow rocks in which the mineral bodies were later 

(2) The silicification of the volcanic fragmental and 
flow rocks by metasomatic processes as is indicated 
by the presence of original structures of the vol- 
canics in the silicified materials, and by the pres- 
ence of entirely surrounded fragments of only 
partly silicified volcanic rocks in the quartz areas. 

(3) The development of pyrite in the silicified areas, 
accompanying or immediately following the silci- 
fication of the volcanics. 

(4) The development of chloritoid to some extent in all 
the pyrophyllite bodies and in abundance in parts 
of these deposits that are near iron rich forma- 

(5) The development of sericite by the replacement of 
the previously silicified volcanic fragmental and 
flow rocks. 

(6) The development of pyrophyllite by replacement of 
the previously silicified and mineralized tuffs and 
breccias, closely associated with or immediately 
following the formation of the sericite. 


The pyrophyllite forming solutions were evi- 
dently of hypogene origin, but their source is not 
so easily demonstrated. The only intrusive igneous 

rocks that are exposed near any pyrophyllite de- 
posits in the area are diabase dikes, which are 
clearly later than the pyrophyllite mineralization. 
While none of them are known to be exposed in 
or near a pyrophyllite deposit there are a great 
many granite type intrusive rocks exposed at 
widely scattered localities in the pyrophyllite 

During the latter half of the nineteenth cen- 
tury there were a number of active gold and cop- 
per mines throughout the Carolina Slate Belt that 
were important enough to receive considerable 
attention in reports of the North Carolina Geolog- 
ical Survey between 1856 and 1917. Nitze and 
Hanna (1896) pointed out that the gold and cop- 
per deposits throughout the Carolina Slate Belt 
are very similar and that much silicification had 
accompanied the formation of the ores. They at- 
tributed this mineralization to hot carbonated, 
alkaline waters of deep seated origin. Laney 
(1910) found much silicification associated with 
the ore bodies (gold and copper) at Gold Hill, 
and concluded that the mineralization had been 
produced by hot solutions given off from a granite 
that had been intruded into the volcanics in the 
immediate vicinity of the ore bodies. Pogue 
(1910) found practically the same conditions in 
the Cid district of Davidson County, except that 
there were no known intrusive igneous rocks to 
have furnished the solutions. He concluded, how- 
ever, that there were large igneous masses in- 
truded into the rocks of the district from below, 
but that these rocks did not reach the surface. 

If Nitze and Hanna are correct in their state- 
ments that the gold and copper mines of the en- 
tire slate belt are in general alike, and if Pogue 
is correct in assuming a large intrusive magma 
below the Cid district that belonged to a period 
when large amounts of igneous rocks were in- 
truded into the Piedmont Plateau and brought 
near the surface, it seems that the same condi- 
tions must have existed in the pyrophyllite re- 
gion and that the gold ores of the various mines 
were formed by hot solutions from igneous mag- 
mas below. There is a close relation between the 
pyrophyllite deposits and the metalliferous de- 
posits at a number of places. One that may be 
used as a type example is the mine of the Stand- 
ard Mineral Company near Robbins, Moore Coun- 
ty, where the pyrophyllite schist grades directly 
into the silicified tuff at the old Cagle gold mine. 
This seems to indicate that the same source that 


furnished the hot solutions to deposit the gold and 
copper ores in the slate belt also furnished the hot 
solutions to produce the pyrophyllite bodies. 


Different investigators have indicated that py- 
rophyllite may form under conditions varying 
from high temperature and pressure to low tem- 
perature and pressure such as exist near the 

The information available on the origin of 
chloritoid. seems to indicate that it forms at fairly 
high temperatures and according to Niggli 
(1912) is directly dependent upon fairly high 

Graton (1906) classed the gold-quartz veins of 
the Southern appalachians as high temperature 
in origin, while Laney (1910) and Pogue (1910) 
both indicated that the gold and copper ores of 
the Gold Hill and Cid districts were formed under 
conditions of temperature and pressure varying 
from high to intermediate. That the pyrophyllite 
bodies were formed by hot solutions given off 
from the same source and acting at about the 
same time is indicated by the close association of 
the pyrophyllite bodies with the old gold mines, 
especially the Cagle gold mine near Robbins, 
Moore County and at the Brewer gold mine 
(Powers, 1893) in South Carolina. Hafer (1913) 
noted the presence of copper bearing pyrite in 
the mine of the Southern Talc Company at Glen- 
don, Moore County. 

It is possible that at the pyrophyllite deposits 
there was a gradual change from high tempera- 
ture and pressure to low temperature and pres- 
sure of hydrothermal alteration near the surface 
during the period of activity of the hot solutions. 
The writer, however, agrees with Buddington 
(1916) and Jahns and Lance (1950) and believes 
that the pyrophyllite deposits of the Carolina 
Slate Belt in North Carolina were formed under 
conditions of intermediate temperature and pres- 

While considering the source of the solutions 
and the conditions under which the pyrophyllite 
was formed the problem of a line of entrance for 
rising solutions should not be overlooked. 

As has been stated above, the pyrophyllite de- 
posits occur as elongate bodies or lenses several 
times as long as they are wide. In at least four 
localities, near Robbins, Moore County, along 

Deep River north of Glendon in Moore County, 
near Hillsborough in Orange County, and north 
of Stem in Granville County, the pyrophyllite 
bodies occur as a long zone of lenses from 50 feet 
to 500 feet wide and from 250 feet to 2000 feet 
long that can be traced for considerable distances 
along strike. The mineral bodies are all found in 
acid tuffaceous rocks and in some cases, particu- 
larly along Deep River north of Glendon in Moore 
County, on the limbs of anticlines (as they were 
worked out and mapped in the field). 

It seems unreasonable for a special type of vol- 
canic tuff to have been formed as long narrow 
bands so widely separated while at all other points 
there were such wide variations in the material. 
The conclusion, therefore, is that there was either 
faulting or some lines of weakness developed 
along which the solutions entered to form the 
mineral deposits. 

Recently, Conley (1962 a) has shown that the 
pyrophyllite deposits along Deep River, north of 
Glendon, and those southwest of Robbins in Moore 
County, were formed along fault zones. There has 
not been enough detailed mapping carried out to 
determine the true conditions at the other de- 
posits in the slate belt. Stuckey (1928) pointed 
out that the pyrophyllite bodies were formed by 
the replacement of acid tuffs and breccias of both 
dacitic and rhyolitic composition and that the 
tuffs and breccias remained in a state of open 
texture and tended to mash and shear instead of 
folding. It is logical to assume, therefore, that all 
the pyrophyllite bodies were formed along lines 
of weakness, either fault zones or shear zones. 


Sufficient evidence is not available to determine 
accurately the reserves of pyrophyllite in North 
Carolina, but there is sufficient information to 
establish the presence of fairly dependable indi- 
cated reserves. Of some 15 known occurrences of 
pyrophyllite in North Carolina only 5 or 6 have 
been developed enough to indicate important re- 
serves of mineable pyrophyllite. These major 
deposits occur near Robbins and Glendon, Moore 
County, near Snow Camp, Alamance County, near 
Hillsborough, Orange County and near Stem, 
Granville County. All of these deposits, with two 
exceptions occur along prominent hills or ridges. 
The Glendon deposits occur in gently undulating 
topography, while that near Robbins occurs in a 
relatively flat area covered largely by a thin 
veneer of Coastal Plain sand. 


To-date, with one exception, all the pyrophyl- 
lite mining in the State has been carried out 
largely from shallow pits and open cuts that have 
seldom reached a depth greater than 50 or 75 
feet. The one exception to these conditions is at 
the mine of the Standard Mineral Company at 
Robbins, Moore County, where a shaft 650 feet 
deep and drifts and stopes are being used. In 
none of these pits, open cuts, or mines has there 
been any major change in the pyrophyllite or 
associated minerals with depth. 

Even though pyrophyllite should not be found 
in commercial amounts to depths of over 200 feet, 
there is enough available to that depth, in the 
more promising deposits, to support an important 
industry for many years under efficient mining, 
milling and concentration practices. 

The processes of milling have been such that 
everything that went into the mill had to be pure 
enough to make a good finished product. It is only 
recently that any attempt has been made to use 
separating and concentrating machinery in the 
removal of grit and other impurities. This has 
meant that a large amount of material which con- 
tained 50 percent or more of pyrophyllite has 
been going on the dumps as waste. If the methods 
of milling could be improved to the point where 
all material containing as much as 40 to 50 per- 
cent pyrophyllite could be utilized, it would prac- 
tically double the available amount on the basis of 
milling practices formerly carried out. 

Pratt (1900) pointed out that the pyrophyllite 
is continuous and of considerable, though un- 
known depth. Hafer (1913) suggested that pyro- 
phyllite should be found to the same depths that 
the gold mines of the area have reached, and in- 
dicated that gold had been mined to a depth of 
500 feet. This statement seems very reasonable 
when it is realized that there is a close relation 
in the distribution of the gold and pyrophyllite 
mines, and also a strong possibility that the solu- 
tions forming both come from the same source. 

Stuckey (1928) stated: "Taking into consider- 
ation the mineralogy and origin of the deposits, 
the source of the solutions and the relations in 
the distribution of the gold and pyrophyllite de- 
posits, it seems reasonable to expect pyrophyllite 
in commercial amounts to a minimum depth of 
500 feet. This statement does not mean that every 
pyrophyllite deposit can be developed into a mine 
at that depth. It does mean, however, that all 
indications point to a depth of that magnitude 

for the larger bodies which really show promise 
at the surface." 

The results obtained in exploring for pyrophyl- 
lite over the intervening years have borne out 
this statement. Some small prospects have been 
explored that did not prove continuous with 
depth, but drill holes more than 500 feet deep 
have failed to reach the limits of the major de- 

The pyrophyllite deposits occur as irregular 
lenses 50 to 500 feet wide and 500 to 1500 or more 
feet long. The bodies of workable pyrophyllite 
usually occur near the center of the deposits and 
vary in width from a few feet to more than 100 
feet. Pyrophyllite has a specific gravity of 2.8 to 
2.9 and weighs 175 pounds per cubic foot. Each 
100 feet of length and depth of a pyrophyllite 
body 100 feet wide should yield 50,000 tons allow- 
ing for a 60 percent recovery. Using these figures 
and assuming recovery to a depth of 400 to 500 
feet, a reserve of some 10 to 12 million tons of 
pyrophyllite is indicated in North Carolina. 

During the past 15 years it has been frequently 
stated that all the really promising pyrophyllite 
deposits in North Carolina had been discovered 
and were controlled by three or four major min- 
ing companies. Recently, detailed prospecting by 
two major companies has resulted in the discovery 
of promising occurrences of pyrophyllite in three 
new areas. These deposits have not been explored 
and detailed information on them is not available. 
These discoveries are interesting, however, as 
indicating that undiscovered bodies of pyrophyl- 
lite are still available in North Carolina to those 
willing to do the necessary prospecting to find 


The first reference to pyrophyllite mining in 
North Carolina was by Emmons (1856, p. 217) 
who stated: "Large quantities have been ground 
the last year in Chatham County for the New 
York market." He, also stated (p. 53) "The rock 
does not split readily with gunpowder; when 
quarried in this mode, as at Hancock's, it breaks 
out in illshapen shattered masses. Hence it should 
be cut out with a sharp pick or an edged instru- 
ment of suitable form." 

At first prospecting and mining were carried 
out by pits, shallow shafts, drifts and open cuts. 
As demands for larger quantities increased and 
off color material became salable, open cuts — 


made possible by information from diamond drill- 
ing and by modern earth-moving machinery have 
furnished most of the production. The largest, 
and only modern underground pyrophyllite mine 
in North Carolina, is operated near Robbins, 
Moore County, through a 650 foot shaft, drifts 
and stopes. 


The processing of pyrophyllite has changed 
slowly through the years as demands and uses for 
the mineral have increased and changed. Prior to 
about 1855 it was used only locally — for stove 
linings, fireplaces, chimneys, mantels and grave- 
stones — and was cut and shaped to fit the par- 
ticular need. The production of pyrophyllite 
crayons was started about 1880 and continued 
until about 1920. Ground pyrophyllite was first 
produced in 1855, (Emmons 1856, p. 217) . From 
1855 to 1913 grinding was carried out, first at 
Hancock's Mill and later at Glenn's Mill, both 
located on Deep River near the present village of 
Glendon, Moore County. The grinding stock was 
carefully selected, air dried, and crushed. It was 
then crushed by hand, ground with millstones and 
passed through bolting cloth. 

In 1902 the first mill constructed exclusively 
for grinding pyrophyllite was built near a deposit 
along Deep River, north of Glendon. This was 
followed in 1904 by a second mill on another de- 
posit about a mile away. Both mills were alike 
in that the grinding stock was air dried and 
crushed. In one mill the crushed material was 
passed through a hammer mill, ground with mill- 
stones, fed into a ball mill, ground 8 hours and 
screened. In the other mill, the crushed material 
was ground with millstones, the fines removed by 
air, and the coarse material fed into a ball mill, 
ground, and screened. Both of these mills were 
abandoned by the end of 1921. 

Before 1918, all the known pyrophyllite de- 
posits of any importance were located along the 
north side of Deep River, in the general vicinity 
of Glendon, Moore County. In that year, what 
later proved to be the largest known pyrophyllite 
deposit in the state was discovered about 2 miles 
southwest of Robbins, Moore County, when wagon 
wheels brought up a fine white material that 
proved to be pyrophyllite. The first modern grind- 
ing plant was built on this property about 1921. 
The process first used consisted of crushing, 
grinding in a hammer mill and screening. The 

hammer mill did not prove satisfactory for grind- 
ing, and after some modifications, the process 
was abandoned. A new process was installed, con- 
sisting of crushing and grinding in a roller mill, 
and screening. As the ceramic market for pyro- 
phyllite has become more important, conical peb- 
ble mills for fine grinding have been installed in 
this and other plants in the State. 

At the present time three companies — the 
Standard Mineral Company at Robbins, the Gen- 
eral Minerals Company at Glendon, and the 
Piedmont Mineral Company at Hillsborough are 
mining and processing pyrophyllite for market. 
A fourth company, the North State Pyrophyllite 
Company at Greensboro is mining pyrophyllite 
and producing a variety of pyrophyllite refrac- 
tories but is not selling pyrophyllite as such. 
None of these companies is carrying out benefi- 
ciation or true mineral dressing on crude pyro- 
phyllite. By selective mining, blending, grinding 
and screening, a wide variety of grades, stand- 
ardized both as to grain size and chemical com- 
position, is being produced for fillers and specialty 
products and for use in ceramic bodies and re- 

In the processes used to-date, only pyrophyllite 
pure enough to make a salable finished product 
has been used. As a result, much good material 
containing 40 to 60 percent pyrophyllite has been 
discarded. In view of the somewhat limited re- 
serves and increasing demands, too much good 
material is being left in the ground or thrown on 
the dumps. However, as demands have increased, 
improved methods of grinding and screening have 
reclaimed much material formerly discarded. Re- 
search on the removal of iron, free silica and 
other impurities has been carried out. As a result, 
larger tonnages of pyrophyllite of higher quality 
than that now being produced should be made 
available to industry as demands increase. 


Pyrophyllite has a wide range of uses which 
are dependent largely upon the remarkable physi- 
cal properties of the mineral. Most of these uses 
are similar to those of talc, to the extent that the 
two minerals are often used interchangeably. Py- 
rophyllite is a hydrous aluminum silicate with the 
formula H 2 Al 2 Si 4 0i2. It occurs in several common 
habits, the best known, perhaps, being the rosette- 
like aggregates of radially disposed fibers and 
elongate flattened crystals. A flaky or foliated 


variety with a slaty cleavage is common along 
the north side of Deep River and near Robbins 
in Moore County. A third variety consists of 
masses of grains and fibers that lack orientation 
or layering. In some of the finer-grained occur- 
rences, the pyrophyllite individuals are rosette- 
like in detail although this is rarely apparent to 
the unaided eye. 

While the chemical formula of theoretically 
pure pyrophyllite is rather simple, most commer- 
cial pyrophyllite contains varying small quanti- 
ties of the elements, iron, calcium, magnesium, 
sodium, potash and titanium. The chemical com- 
position can be useful in predicting the behavior 
of pyrophyllite where very exact controls are 
required in the manufacture of certain products. 
In ceramic bodies, for example, such properties 
as color, shrinkage and absorption of tile bodies 
can be predicted in terms of the raw pyrophyllite 
used in them. 

The nature and uses of several types of pyro- 
phyllite from North Carolina have been effec- 
tively summarized in a booklet published by the 
R. T. Vanderbilt Company (1943) of New York. 
For further details on the properties of pyro- 
phyllite the reader should consult Grunner 
(1934), Hendricks (1938), and Ross and Hend- 
ricks (1945). 

Prior to about 1855, pyrophyllite was used 
locally for tombstones, and such stones, still well 
preserved, may be seen in two or more cemeteries 
near Glendon. Emmons (1856) described it as an 
excellent substitute for soapstone in stove linings, 
fireplaces, chimneys and mantles. He stated that it 
was not suitable for paint as it became translu- 
cent when mixed with oil, but described it as a 
filler that helped retain the perfume in soap and 
added that large quantities were ground for the 
New York market in 1855. He described it as 
suitable for anti-friction powder and use in cos- 
metics and quoted Dr. Jackson to the effect that 
it would make a very refractory material for 
stoneware and crucibles. 

At present, pyrophyllite is used chiefly in the 
manufacture of insecticides, rubber, paint, ceram- 
ics, refractories, plastics, and roofing paper. It 
has a number of minor uses for products including 
cosmetics, wallboard, rope and string, special 
plaster, textile products, paper, linoleum and oil- 
cloth, and several types of soap. The best pro- 
duction figures available indicate that about one 
half of the current annual production goes into 

insecticides, rubber and paint, one third into 
ceramics and refractories and the remainder into 
plastic, roofing paper, linoleum, cosmetics and a 
host of minor uses. 

According to Jahns and Lance (1950) : "A 
large part of the domestic production of pyrophyl- 
lite is incorporated into paints and particularly 
non-reflecting and other special types in which 
flake pigments of light color are desired. High oil 
absorption of ground pyrophyllite and its free- 
dom from grit also are desirable properties for 
paint use. Ground material is employed as a filler 
in rubber goods, certain roofing and flooring ma- 
terials, special plasters, plastics, insecticides, tex- 
tile products, paper, linoleum and oilcloth, rope 
and string, several types of soap and in some 
fertilizers. It serves as a "loader" in paper and 
textile fabrics, where its whiteness and resistance 
to the effects of fire and weather are particularly 
desirable. This resistance also partly accounts for 
its use in roofing papers and other asbestos and 
asphalt goods. Its corrosion resistance makes it 
an especially satisfactory filler in battery cases. 
There are indications that it also may serve effec- 
tively as a low noise filler in phonograph records. 

"With a low bulk density and slight acidity in 
ground form, high absorptive characteristics, and 
superior qualities as a flake-form dusting agent, 
pyrophyllite is an excellent carrier for such active 
insecticides as DDT, nicotine, pyrethrum and 
rotenone. The flakiness of the mineral leads to 
desirable adhesion on leaves and other parts of 
dusted plants, and its softness and freedom from 
grittiness when finely ground make for reduction 
of wear on nozzles and other parts of mechanical 
insecticide dispensers. 

"Pyrophyllite of great purity and whiteness has 
been used as a base for cosmetics and toilet prep- 
arations, but the total amount is not large. The 
lubricating properties of the mineral underlie its 
use in some greases, in tires and other rubber 
goods, on machine-driven box nails, and in vari- 
ous kinds of dies. On the other hand, it also is 
employed as a fine, "soft" abrasive in the scour- 
ing and polishing of certain foodstuffs, as well 
as some painted or lacquered surfaces. It serves 
as a high-quality packing and insulating material, 
as a constituent of adhesive, corrosion-resistant 
covering compounds, and as an absorbent for oil 
substances in a wide variety of products. It, 
also, can be processed for use in crayons and 


"As a constituent of ceramic bodies, pyrophyl- 
lite is being more and more widely used. It is a 
good substitute for feldspar and quartz in wall- 
tile bodies, as it decreases their shrinkage and 
their crazing by thermal shock or moisture ex- 
pansion. It also is employed as a source of alumi- 
num in enamels, and as a raw material for semi- 
vitreous dinnerware and some types of refrac- 

Uniformity of grain size and mineral content 
is becoming important for all uses. For ceramics, 
whiteware, and wall tile, where the size of the 
finished product must be controlled accurately, 
pyrophyllite is one of the best materials available 
provided it is perfectly uniform in grain size and 
composition. For use in special refractories, such 
as car tops for tunnel kilns, monolithic furnace 
lining and furnace lining requiring rapid tem- 
perature changes, pyrophyllite makes an excel- 
lent body that is shock-resistant. 


Beginning on the northeast in Granville Coun- 
ty, near the Virginia line, and continuing in a 
southwesterly direction to the southwestern part 
of Montgomery County is an irregular zone, along 
the eastern part of the Carolina Slate Belt, that 
contains all the known occurrences of pyrophyl- 
lite in North Carolina. Prospects, outcrops and/or 
mines are known to occur in Granville, Orange, 
Alamance, Chatham, Randolph, Moore and Mont- 
gomery counties. 


Daniels Mountain 

Pyrophyllite bodies occur in three localities in 
Granville County. One of these is on Daniels 
Mountain, a prominent ridge that rises nearly 
200 feet above the surrounding countryside. 
Daniels Mountain is located approximately 9 
miles slightly northwest of Oxford, about 1.5 
miles east of North Carolina Highway 96 and 
just south of Mountain Creek. The area is un- 
derlain with acid volcanic rocks. Small amounts 
of pyrophyllite occur on the north end of this 
ridge. No prospecting had been done at the time 
the writer visited the ridge. Espenshade and Pot- 
ter (1960) described Daniels Mountain as fol- 
lows : "Another deposit of pyrophyllite occurs on 
a prominent ridge rising nearly 200 feet above 

the surrounding countryside, about 14 miles 
northeast of Bowlings Mountain deposit, 9 miles 
northwest of Oxford, and about l 1 /^ miles east 
of North Carolina Highway 96. Float and low 
outcrops of dense siliceous rock are abundant for 
about three-quarters of a mile along the ridge. 
Chloritoid occurs in some rock, disseminated 
hematite and magnetite are also present. Blocks 
of massive pyrophyllite, 1 to 2 feet long, are dis- 
tributed along a distance of 600 to 700 feet at 
the north end of the ridge. Other aluminous min- 
erals have not been discovered." 

Bowlings Mountain 

A major pyrophyllite deposit is present on 
Bowlings Mountain, a prominent hill that is lo- 
cated about 3 miles northwest of Stem and 10 
miles southwest of Oxford, Granville County. The 
hill rises to an elevation of about 700 feet above 
sea level (approximately 200 feet above the sur- 
rounding countryside), has a trend of about N 
15° E and conforms to the pattern of a series of 
rather pronounced ridges to the northwest. The 
pyrophyllite deposit which lies along the crest 
and northeastern slope of the mountain is ap- 
proximately 500 feet wide and more than 1500 
feet long. The strike is N 15° E and the apparent 
dip is 70° to 80° to the northwest, paralleling 
the strike and dip of the country rock. 

Prospecting was first carried out on the south- 
west end of the ridge and near the western slope, 
about the turn of the century, when a pit known 
as the Harris prospect was opened. This pit which 
was 15 to 20 feet long, 6 feet wide and 6 to 10 
feet deep was opened on an outcrop of radiating 
or needle-like crystals of iron-stained pyrophyl- 
lite. About 1940 a shaft was sunk to a depth of 
approximately 80 feet near these old pits. The 
phyrophyllite found in this shaft did not differ 
materially from that found in the surface pits and 
the work was abandoned. 

About 1949 or 1950, Carolina Pyrophyllite 
Company began exploration and development 
work here, consisting of pitting and trenching 
followed by drilling, during the course of which 
a large tonnage of pyrophyllite was discovered. 
Following this exploration work, 2 opencuts were 
developed from which considerable pyrophyllite 
was mined and shipped by truck to a grinding 
plant at Staley, some 80 miles to the southwest, 
before that mill was closed in 1960. 


On the southeast or footwall side of the deposit 
is a medium-grained, dense, quartzitic rock con- 
taining pyrite that seems to represent the foot- 
wall of the deposit. Northwestward from the 
quartzitic rock mineralization is quite apparent. 
Massive and crystalline pyrophyllite occurs in 
very fine-grained schistose zones in sericite schist. 
Tough, white, granular rock containing coarse- 
grained andalusite, quartz, and pyrophyllite is 
present in parts of the deposit. Massive topaz 
identical in appearance with the dense topaz from 
the Brewer mine in South Carolina is abundant 
as float adjacent to the quartzitic footwall. Here, 
it is found concentrated in a series of rather 
poorly defined zones covering an area more than 
100 feet long and 200 feet wide. Individual pieces 
range from less than one-fourth inch to 3 feet 
in diameter. Outcrops in the area are rare, but, in 
recent road cuts along the northern end of the 
mountain, topaz is exposed as a series of narrow, 
irregular veinlike masses in sericite schist. It 
also occurs as stringers a few inches thick in 
phyrophyllite in the southernmost open cut. The 
topaz occurs as boulders in the quartzitic rock, 
filling cracks and fractures, as small knotty 
masses disseminated throughout the rock and as 
large massive pieces which in some cases appear 
to grade into the host rock. The andalusite and 
topaz, older than the pyrophyllite, appear to re- 
place the country rock and in turn are replaced 
by pyrophyllite. 

Long Mountain 

About a mile or two to the northwest of Bowl- 
ings Mountain is a zone of irregular hills from 1 
to 1.5 miles wide and 4 to 5 miles long that is 
known as Long Mountain. This ridge trends 
about north 20 degrees east and lies partly to 
the north and partly to the south of State Road 
1139. The highest point on Long Mountain is a 
knob north of State Road 1139 and along the 
western side of the ridge that is known as High 
Rock Mountain. It rises to an elevation of some 
150 to 200 feet above the surrounding country- 
side and 700 feet above sea level. Pyrophyllite 
outcrops of varying size and promise, some of 
which have been prospected and some of which 
have not, are widely scattered throughout Long 

Robbins Prospect 1 

On the Robbins property, in the vicinity of 
High Rock Mountain is an area about 1000 feet 

wide and 2000 feet long on which radiating pyro- 
phyllite, associated with quartz veins, is common 
but not abundant. No prospecting has been done 
in this general area and the potential for commer- 
cial deposits of pyrophyllite is unknown. Most of 
the pyrophyllite visible is badly iron stained. 

Jones Prospect 

To the east of the Robbins tract and about 1500 
feet north of State Road 1139, some 4 or 5 pros- 
pect trenches that varied in length from 150 to 
300 feet and up to 8 or 10 feet deep were opened 
on the Jones land some 8 or 10 years ago. Details 
of this prospecting are not available but indica- 
tions for pyrophyllite are good. The country rock 
is a medium to fine-grained felsic volcanic tuff 
that has a cleavage which strikes north 20 to 30 
degrees east and dips steeply to the northwest. 
Both foliated and radiating pyrophyllite, some 
of which is iron stained, is farily common. 

R. E. Hilton Property 

Adjoining the Jones land on the east is the land 
of R. E. Hilton on which there is a zone varying 
from 250 to 500 feet wide and about 1000 feet 
long that contains promising outcrops of pyro- 
phyllite. No prospecting has been done on this 
property but bold outcrops of good pyrophyllite 
make it appear promising. 

E. C. Hilton Property 

Along the east side of Long Mountain and 
south of State Road 1139 there are two interest- 
ing areas of pyrophyllite on the land of E. C. 
Hilton. The first of these, which is about 1500 
feet south of State Road 1139 and near a recent 
sawmill site, consists of about three acres on 
which bold outcrops of pyrophyllite mixed with 
similar outcrops of felsic volcanic rocks are abun- 
dant. No prospecting has been done here but the 
outcrops indicate the possible presence of im- 
portant amounts of good pyrophyllite. The other 
area is on a prominent hill about 1500 feet farther 
southeast and beyond a small stream. Surface 
exposures of pyrophyllite are not extensive but 
some interesting outcrops of radiating crystals 
may be seen. Considerable prospecting in the form 
of drilling, the results of which are not known, 
was carried out here about 8 or 10 years ago. The 
country rock at both of these prospects is a medi- 
um to fine-grained, felsic volcanic tuff. 


Robbins-Uzzell Property 

About 1500 feet south of State Road 1139 and 
to the southeast of High Rock Mountain is an 
unnamed ridge that ranges between 500 and 600 
feet above sea level. This ridge which begins near 
the head of an east flowing stream continues in a 
south 20 degrees west direction to and beyond 
Dickens Creek a distance of 1.5 to 2 miles. The 
northeast end of this ridge is a part of the Rob- 
bins tract while the southwest end is a part of 
the Uzzell land. No prospecting has been done on 
this ridge but outcrops of excellent pyrophyllite 
remarkably free of iron stain make it promising 
as a source of pyrophyllite. 

Robbins Prospect 2 

Just east of Knap of Reeds Creek and a short 
distance south of State Road 1139 is a power 
transmission line tower. Beginning near this 
tower and extending to the southwest for a dis- 
tance of 800 to 1000 feet is a pyrophyllite body 
that is 300 to 400 feet wide. The cleavage in this 
mineral body strikes about north 35 to 40 degrees 
east and dips steeply to the northwest. The rocks 
surrounding this deposit consist of medium- to 
fine-grained acid volcanic materials. The north- 
west 150 to 200 feet of the deposit consists largely 
of good quality pyrophyllite that varies from mas- 
sive to foliated. The southeast or footwall portion 
to a width of 75 or 100 feet appears to be in part 
sericite. This is a promising deposit that could 
contain considerable high-grade pyrophyllite. 


Murray Prospect 

Pyrophyllite deposits occur in three localities in 
Orange County. One of these known as the Mur- 
ray property is located on a ridge about 5 miles 
northeast of Hillsborough near the intersection 
of State Roads 1538 and 1548. State Road 1538 
passes just to the north of the property while 
State Road 1548 lies just to the east. Here along 
a ridge in an area of medium to fine-grained acid 
volcanic rocks are old prospect pits up to 30 feet 
long by 10 feet wide and 6 feet deep. Most of the 
pits are about 10 feet long by 4 feet wide and 6 
feet deep. The pits are scattered over an area 75 
to 100 feet wide and 500 feet long. Pyrophyllite 
of the foliated or schistose variety is present on 

the dumps and in the sides of the pits as well as 
in an occasional outcrop. Chloritoid is abundant 
in the walls of some of the pits, especially near 
narrow bands of greenstone in the f elsic volcanics. 
This area probably contains pyrophyllite of value. 

Hillsborough Mine 

Immediately south of Hillsborough are three 
prominent hills which trend northeast and paral- 
lel the major geologic structure of the area. From 
northeast to southwest these hills are often desig- 
nated Hill No. 1, Hill No. 2 and Hill No. 3. Al- 
though the three hills appear to be much alike in 
many ways, the developed mineralization is 
limited to Hill No. 1, the northeastern most of 
the three. Here, prospecting was started in 1952 
by the North State Pyrophyllite Company fol- 
lowed by mining a few years later. The zone of 
mineralization as exposed by the open cut mining 
operations is some 1500 feet long and from 100 to 
250 feet wide. It strikes approximately N. 50° E. 
and dips from 60 to 80 degrees to the northwest. 
The mineral body has a footwall of dense siliceous 
rock that forms the crest of the hill or ridge and 
a hanging wall of sericite schist. The chief min- 
erals in the deposit in the order of decreasing 
abundance are silica, massive and crystalline or 
radiating pyrophyllite, sericite, andalusite and 
topaz. Minor amounts of diaspore have been re- 
ported. Andalusite is abundantly disseminated 
throughout the deposit and seems to be consider- 
ably more abundant than pyrophyllite in much of 
the deposit. It is light blue, greenish blue or gray 
in color, has a pronounced blocky appearance, and 
occurs as small fragments about one-fourth inch 
in diameter, disseminated sparingly to abundant 
throughout the quartzose rock. Topaz occurs spar- 
ingly in the deposit, apparently being limited 
largely to disseminated grains and masses in the 
fractured quartzose footwall rock. 

Recent field work indicates that to the south- 
west mineralization similar to that on Hill No. 1, 
now being worked by Piedmont Minerals Com- 
pany, may be present in workable amounts on the 
northwest side of Hill No. 2 and in a prominent 
knob on the northwest side and near the north- 
east end of Hill No. 3. 

Teer Prospects 

In the southwestern part of Orange County, 
approximately 10 miles southwest of Hillsbor- 


A. Mill 

B. Open Pit Mine 
Plate 2. Piedmont Minerals Company 


ough, and in the general vicinity of Teer, there 
are a number of pyrophyllite outcrops, at least 
three of which have been prospected. On the north 
end of Mitchell Mountain and about one-half mile 
southwest of Teer, North State Pyrophyllite Com- 
pany carried out prospecting and produced a small 
amount of pyrophyllite. A pit 100 feet long, 30 
feet wide at the top and 15 feet deep was exca- 
vated. The strike of the cleavage is N. 55° E. and 
the dip is 75 degrees to the northwest. The 
amount of good grade pyrophyllite was too low 
for economic mining and the prospect was ban- 
doned. About 3 miles almost due north of Teer 
and between State Road 1117 and Cane Creek, on 
the farm of Salina Sykes is a small prospect pit 
that contains minor amounts of radiating pyro- 
phyllite. No production was made and the pit is 
now abandoned. 

About one mile almost due north of Teer and 
between State Roads 1115 and 1116, considerable 
prospecting and some mining for pyrophyllite 
was carried out on the land of Clarence Bradshaw 
by the Carolina Pyrophyllite Company, between 
1958 and 1961. A pit 200 feet long by 100 feet 
wide at the top and about 80 feet deep was exca- 
vated. The pyrophyllite content of the rock was 
originally 24 percent. The cleavage of the rock 
strikes about N. 55° E. and dips 75 degrees to the 


Snow Camp Mine 

The Snow Camp pyrophyllite deposit being 
worked by the North State Pyrophyllite Com- 
pany, is located on Pine Mountain about 3.5 miles 
southeast of Snow Camp. Prospecting was started 
in 1935 and over the intervening years the de- 
posit has been a major producer of massive pyro- 
phyllite. The pyrophyllite is shipped by truck to 
the company's plant at Pomona, North Carolina 
where it is used in the manufacture of firebrick, 
brick-kiln furniture and other refractory prod- 
ucts. The deposit is a lenticular body of massive 
pyrophyllite and fine-grained quartz about 35 
feet long and 250 feet wide. Open pit mining had 
developed walls nearly 100 feet high in the east 
and south sides of the pit until parts of them 
were removed for safety reasons in 1965. A rib of 
high-silica rock is present near the center of the 
deposit. This rib has been quite heavily mineral- 
ized in places and parts of it have been mined out. 

Coarse-grained andalusite was reported to have 
been found in a zone several feet wide in the 
northern part of the deposit, but it did not seem 
to be very abundant. This deposit still appears to 
contain a large reserve of high-grade pyrophyl- 

Major Hill Prospects 

About 2 miles east of Snow Camp there are 
several pyrophyllite outcrops on a prominent hill, 
known locally as Major Hill. Major Hill lies south 
of State Road 1005, between State Roads 2356 
and 2351, and north of State Road 2348. This hill 
is somewhat irregular in shape, but slightly elon- 
gate in a direction a little north of east. Two 
small exposures of pyrophyllite are to be seen in 
old prospect pits near the west end of the hill, 
but they do not appear to be of commercial size. 
Beginning about midway of the hill from west to 
east and along the southern slope some 250 feet 
from the crest is a zone of pyrophyllite about 
1000 feet long and 50 to 100 feet wide that ap- 
pears from outcrops to contain a considerable ton- 
nage of high-grade massive pyrophyllite. Due to 
wooded conditions and lack of outcrops the geolog- 
ical setting could not be satisfactorily determined. 
It appears, however, that the pyrophyllite is in 
an area of medium- to fine-grained tuffaceous 
rocks of volcanic origin and acid composition. This 
deposit is on land belonging to the North Carolina 
National Guard. 

Immediately to the east of the deposit on the 
National Guard land is a deposit 100 to 150 feet 
wide and 350 to 500 feet long on lands of the 
Holliday estate. This deposit contains both pyro- 
phyllite and sericite which have a cleavage that 
strikes N. 50° to 60° E. and dips steeply to the 
northwest. This deposit appears to contain a con- 
siderable tonnage of minable material. 

To the northeast of this deposit and near the 
east end of Major Hill is another deposit of 
promise on the Holliday estate. The outcrop is 
irregular in shape but appears to be 150 to 300 
feet wide and 400 to 500 feet long. Pyrophyllite 
and sericite, both of which have a cleavage that 
strikes N. 50° to 60° E. and dips steeply to the 
northwest, are present in varying amounts in this 

To the south and southeast of the above de- 
scribed deposits is another deposit on the south- 
east tip of Major Hill and on lands of the Holliday 
estate. This deposit is 150 to 250 feet wMe and 


400 to 500 feet long. It contains both pyrophyllite 
and sericite which have a cleavage that strikes 
N. 50° to 60° E. and dips steeply to the north- 

Because the above described three deposits, on 
the Holliday estate are all in wooded areas and 
rock outcrops are not too abundant it was not 
possible to establish completely the geological 
setting. It appears, however, that all three are in 
areas of medium- to fine-grained tuffaceous rocks 
of volcanic origin and acid composition. In the 
spring and summer of 1966 these deposits were 
under option to and being prospected by the North 
State Pyrophyllite Company. 

On the Richardson land, a short distance north- 
east of Major Hill and just west of State Road 
2351, is an interesting occurrence of pyrophyllite. 
The outcrop area which is elongated in a north- 
east direction appears to be about 100 feet wide 
and 350 to 500 feet long. Both massive and radiat- 
ing pyrophyllite are present. 

About 2 miles east of Snow Camp and a short 
distance north of State Road 1005, the Carolina 
Pyrophyllite Company is quarrying sericite on a 
small ridge on a hill adjacent to the Foust lands. 
The sericite is being shipped by truck to Glendon 
where it is ground and blended with pyrophyllite. 
Open pit mining indicates a large tonnage of rock 
which may extend into the Foust lands to the 

Hinshaw Prospect 

The only known pyrophyllite deposits in Chat- 
ham County are on the farm of Don Hinshaw in 
the northwestern corner of the county. This prop- 
erty is about 2 miles east of State Road 1004 and 
a short distance north of State Road 1343. It can 
be reached by leaving State Road 1004 at State 
Road 1343 about 2.5 miles south of the Chatham- 
Alamance line. Follow State Road 1343 about 1.5 
miles northeast to the Hinshaw farm. The out- 
crops are in a wooded area a short distance north 
of the Hinshaw home. Here, some years ago, 
Carolina Pyrophyllite Company opened a pit some 
10 feet wide, 15 feet deep and 25 to 40 feet long. 
Near this pit, pyrophyllite is scattered through 
rocks over a distance of 100 feet long and 25 to 
50 feet wide. To the northeast are other outcrops 
that look promising. Enough pyrophyllite out- 
crops are present in the area to indicate that it 
is worth prospecting. 


Pyrophyllite is known to occur in Randolph 
County in two areas. One of these is in the north- 
eastern corner of the county about 3.5 miles west 
of Staley. The other is on the southern slopes of 
Pilot Mountain just north of State Highway 902 
and about 8 miles east of Asheboro. 

Staley Deposit 

The Staley deposit, now worked out, was at one 
time the second largest pyrophyllite mine in the 
State. The main part of the deposit lay along the 
crest and northwest side of a rather steep hill as 
a lenticular body 100 to 200 feet wide and 350 
feet long. The cleavage strike was approximately 
N. 50° E. and the dip was 60 to 70 degrees to the 
northwest. When abandoned the open cut was 
about 180 feet wide, 300 feet long and 250 feet 
deep. The hanging wall of the deposit consisted 
of a volcanic ash largely altered to a sericite 
schist. A central zone 10 to 150 feet thick con- 
tained a core of high grade massive to crystalline 
pyrophyllite 20 to 40 feet thick. The footwall was 
a massive high-silica rock about 60 feet thick. 
Quartz, sericite, pyrophyllite and chloritoid were 
prominent throughout the deposit. High alumina 
minerals were present in relatively small amounts. 
Andalusite was probably most abundant and local- 
ly formed aggregates of crystals several inches 
long. At depth the mineralized zone became too 
narrow to work and the deposit was abandoned. 
Over the years, pyrophyllite production amount- 
ed to approximately 400,000 tons. 

Pilot Mountain Prospect 

About 8 miles southeast of Asheboro, on the 
southern slope of Pilot Mountain, and a short 
distance north of State Highway 902, there are at 
least three outcrops of pyrophyllite on the Caddell 
land. The pyrophyllite occurrences are adjacent 
to an old abandoned road known as the John 
Wright road. The John Wright road begins at 
State Highway 902 a short distance east of State 
Road 2908 and continues in a northerly direction 
along the southern slope of Pilot Mountain. About 
one-half mile north of State Highway 902 and 
immediately along the east side of the John 
Wright road, pyrophyllite crops out as irregular 
masses of varying size over an area 100 to 150 
feet wide and 200 to 300 feet long. The area of 
outcrop is elongated in a general northeast-south- 


west direction. No prospecting has been done on 
this occurrence but it appears interesting. 

About one-half mile to the north of the above 
described occurrence there is another deposit of 
pyrophyllite immediately along the west side of 
the John Wright road. Like the others, it has a 
northeast-southwest trend and from the outcrops 
present appears to be approximately 100 feet 
wide and 200 feet long. No prospecting has been 
done on this deposit but it appears interesting. 

About midway between the two pyrophyllite 
occurrences described above, the John Wright 
road forks and what appears to be the main road 
continues in a direction a little north of west. 
Along this road between one-half and three- 
fourths of a mile from the forks, there are a num- 
ber of old prospect pits immediately along the 
north side of the road. These old pits contain very 
little indications of pyrophyllite. However, about 
1000 to 1200 feet almost N. 45° W. from these 
old pits is the north end of a northeast-southwest 
trending ridge that does contain considerable 
signs of pyrophyllite. Along this ridge for a dis- 
tance of 1000 to 1500 feet radiating crystals of 
pyrophyllite associated with vein quartz are very 
abundant. No prospect pits are to be seen on the 
ridge but it has been explored by drilling. Details 
of this drilling are not available but reports are 
that the pyrophyllite is high in iron and mixed 
with considerable quartz. This is partly verified 
by the brown color of the pyrophyllite in outcrops 
and by the amount of quartz along the ridge. 
This ridge could contain pyrophyllite of value. 

Due to a dense forest growth and the lack of 
abundant outcrops the geologic setting of the 
pyrophyllite deposits along the John Wright road 
is not definitely established. It appears, however, 
that these deposits are associated with acid frag- 
mental rocks of volcanic origin. 


Moore County contains the largest reserves of 
pyrophyllite known to occur in any locality in the 
United States. This mineral has been mined near 
Glendon for more than 100 years. Old grave stones 
in that vicinity show dates between 1840 and 
1845 and according to Emmons (1856, p. 217) 
large quantities of pyrophyllite (agalmatolite) 
were ground the last year for the New York 

What Emmons (1856, p. 52) regarded as agal- 
matolite and what is now known to be pyrophyl- 

lite was first thought to be soapstone. He stated: 
"A rock which occurs in extensive beds, and 
known in the localities where it is found as a soap- 
stone, can by no means be placed properly with 
the magnesian minerals." He found the mineral 
to contain aluminum, classed it as agalmatolite 
and gave an analysis of agalmatolite and an analy- 
ses of soapstone for comparison. 

There seems little doubt that the first attempts 
at pyrophyllite mining were made at what is now 
known as the Womble mine. This mine is located 
north of Glendon and about a mile from Hancock's 
Mill mentioned by Emmons. He stated (p. 53) 
"The first beds which I examined are at Han- 
cock's Mill on Deep River." On page 54, he re- 
ferred to "The agalmatolite, near Hancock's 
Mill and sometime called Womack's soapstone. 
. . ." On a map of the Deep River Coal Field at 
the end of his 1856 report, Emmons showed ap- 
proximately at their correct locations, Hancock's 
Mill, the Womble home and soapstone. The name 
Womble has been known in the community for at 
least 100 years while the name Womack has not. 
As a result, it seems quite certain that the first 
mining near Hancock's Mill on Deep River was 
done at the mine known today as the Womble 

Deposits of pyrophyllite occur in 3 areas in 
Moore County as follows: (1) in a fault zone sev- 
eral miles long that lies along Deep River north 
of Glendon; (2) in a small area southwest of 
Hallison; and (3) in a fault zone several miles 
long that lies southwest of Robbins and along 
Cabin Creek. Eight pyrophyllite mines and pros- 
pects, three of which are being mined, are located 
on the Glendon fault from McConnell northeast 
of the county line. Other prospects opened on the 
Glendon fault to the northeast in Chatham Coun- 
ty and southwest of the McConnell pit in Moore 
County have been abandoned for more than 40 
years. Southwest of Hallison are three prospects 
that are currently idle. Two active mines and one 
idle prospect are located on the Robbins fault. 

McConnell Prospect 

The McConnell prospect is located approximate- 
ly 0.5 of a mile northeast of the village of Mc- 
Connell. McConnell is located south of High Falls 
and Deep River at the point where State Road 
1487 intersects State Highway 22. Prospecting 
here originally consisted of an open cut about 400 
feet long, 10 to 15 feet wide and 15 feet deep as 


a maximum, which extended across the strike of 
the formations near the contact between acid tuff 
and a normal slate to the south. The pits are now 
almost completely filled up and grown over, but 
the dumps contain sericite schist, and foliated 
pyrophyllite. A highly sheared sericitized felsic 
tuff, in part silicified, is exposed along an access 
road west of the prospect. According to Conley 
(1962) the shear zone of the Glendon fault at this 
point is only about 40 feet wide and the mineral- 
ized zone approximately 10 feet wide. 

Jackson Prospect 

The Jackson prospect is located in a bend on 
the south side of Deep River some 2 miles north 
of the Norfolk Southern Railway, 3 miles north- 
east of the McConnell prospect and about 3 miles 
a little northwest of Glendon. The shear zone of 
the Glendon fault is about 200 feet wide in this 
area. The deposit is located on the fault zone in 
acid tuff near the contact with volcanic slate 
(bedded argillite) on the south. Two prospect pits 
have been opened to depths of 10 to 15 feet before 
the walls slumped. Considerable white foliated 
schist is exposed in the pits, but no commercial 
pyrophyllite was in sight when the pits were last 

Bates Mine 

The Bates mine is located on the northeast bank 
of Deep River approximately 2 miles northeast of 
the Jackson prospect and 1.5 air line miles north- 
west of Glendon. Prospecting is reported to have 
been started in 1903. A mill was built in 1904 and 
operations continued until 1919 when the mine 
and mill were closed. 

The development work done consists of two 
open cuts and a shaft on the footwall side and a 
large open cut on the hanging wall side of the 
property. The footwall consists of an acid vol- 
canic breccia composed of fragments 1 to 2 inches 
in diameter. The hanging wall is a rhyolite some- 
what sheared and weathered along the mineral 
body. The total width of the mineralized zone is 
between 150 and 300 feet along the zone of the 
Glendon fault. 

On the footwall side and along the zone of brec- 
cia two open cuts were made, one on either side 
of a small stream about 600 feet east of the river. 
Each of these cuts was some 20 to 30 feet wide, 
20 feet deep and 30 feet long. Small amounts of 

good pyrophyllite were found. Between these open 
cuts and the river a shaft was sunk to a depth of 
approximately 60 feet and drifts were run out. 
Small amounts of compact nonfoliated pyrophyl- 
lite are reported to have been found in this shaft. 

On the hanging wall side, an open cut 250 feet 
long was made across the strike of the forma- 
tions. At the north end of the opening another 
cut was opened at right angles to the first, the 
two combining in the shape of the letter "T". The 
width of the open cut was about 20 feet and the 
maximum depth about 40 feet. A drift was driven 
from the open cuts a short distance into the hill- 
side. No commercial pyrophyllite was found in 
these openings. The operations were abandoned 
because of a lack of sufficient commercial ma- 

Attempts were made in the late 1920's and 
again in the 1930's to reopen the mine and acti- 
vate the mill. Neither attempt developed sufficient 
pyrophyllite and the property has been idle since. 

Phillips Mine 

About 0.4 mile northeast along strike from the 
Bates mine and about 1.5 miles a little northwest 
of Glendon is the Phillips mine. It is separated 
from the Womble mine by State Road 1006 and 
lies to the southwest of that road. This property 
which is approximately 1500 feet long has ap- 
proximately the same geologic setting as that of 
the Womble mine described below. The footwall is 
in part iron and in part acid volcanic breccia while 
the hanging wall is largely a medium to fine tuff 
which contains small amounts of rhyolite. The 
mineralized zone is 300 to 500 feet wide, but the 
best pyrophyllite is restricted to a zone 100 to 200 
feet wide along the Glendon fault. Considerable 
mining has been done on this property in the past 
few years and an open cut 1200 feet long, 200 
feet wide at places and 60 to 80 feet deep has 
been developed. The pyrophyllite, which is of the 
foliated variety, varies from white through yel- 
lowish, white to greenish in color, and has a well 
developed cleavage which strikes north 55 to 60 
degrees east and dips from 45 to 70 degrees to 
the northwest. Quartz is present everywhere ex- 
cept in the very best pyrophyllite. Chloritoid is 
present along the footwall of the deposit but not 
as abundantly as in the Womble mine. 

About 1902, a grinding mill was built on the 
southwest end of the property. This mill, which 
was of small capacity, was burned in 1927. In 


1928, a modern grinding mill was erected on the 
Norfolk Southern Railway at Glendon. This mill 
which has been remodeled and improved several 
times since it was constructed is in use today. 

Womble Mine 

The Womble mine joins the Phillips mine along 
State Road 1006 and lies to the northeast. The 
pyrophyllite deposits on the Womble mine as out- 
lined by pits and open cuts are about 1800 feet 
long and 500 feet wide. The pyrophyllite has a 
well developed cleavage which strikes north 55 to 
60 degrees east and dips 45 to 70 degrees to the 

The mineral body has been formed in acid vol- 
canic tuff that varies from rhyolitic to dacitic in 
composition. The footwall, the full length of the 
deposit, is a volcanic breccia which in places is 
rich in iron, chiefly hematite. The amount of iron 
present makes the breccia look much like a low 
grade iron ore and for this reason it is commonly 
known as iron breccia. The hanging wall rock is a 
medium to fine-grained tuff with a small amount 
of rhyolite near the west end. On the footwall 
side and associated with the iron breccia is a large 
amount of dark green chloritoid. This mineral 
which appears as tiny grains 1 to 2 mm. in diame- 
ter passes by gradations into the pyrophyllite 
body and disappears in the pure pyrophyllite. The 
chloritoid is present in small amounts in the 
partly replaced rock masses in the pyrophyllite 
body and to a limited extent in the hanging wall 
rocks. Some of it has weathered to chlorite. 
Quartz is abundant in the deposit. It is present 
as irregular masses or nodules in the impure pyro- 
phyllite and as large cherty or milky masses or 
nodules in the impure pyrophyllite and as large 
cherty or milky masses throughout the deposit. 
Quartz also occurs as small veins or stringers, 
some of which are parallel to the schistosity while 
a great many cut across the cleavage. 

The pyrophyllite which is chiefly of the foliated 
variety varies from white, yellowish white, green, 
gray to almost black in color. The colors other 
than white are doubtless due to iron stain and 
should diminish with depth. 

The deposit has a lenticular structure not only 
along strike but internally and down dip as well. 
Lenses of pure pyrophyllite occur along with 
lenses of quartz or lenses of only partly altered 
country rock. 

The total width ,of the zone of pyrophyllite 
schist in this deposit is as much as 500 feet in 
places but by no means is all this material of 
commercial grade. Much prospecting has been 
done on the property by shaft, pit and open cut, 
none of which have reached a depth greater than 
50 or 75 feet. These test pits show good pyrophyl- 
lite the whole length of the property. The most 
extensive work has been done on the northeast 
end of the deposit where a pit or quarry more 
than 400 feet long, 40 to 60 feet deep and 75 to 
125 feet wide has been opened. Good material has 
been found throughout this pit. A similar pit, 
starting at the boundary of State Road 1006 and 
extending in a northeast direction, is found on the 
southwest end of the property. Recent mining in 
this pit has developed some very good pyrophyl- 
lite. The results of the prospecting done on this 
property indicate a body of commercial pyrophyl- 
lite 100 to 200 feet wide. Under the old methods 
of mining and milling not more than one-fourth 
of this was saved. With proper milling equipment 
it seems that most of the better grade material 
should go directly to the mill. The length and 
width of the mineralized zone indicate the pres- 
ence of a large tonnage of pyrophyllite on this 

Reaves Mine 

The Reaves mine, first known as the Rogers 
Creek Mining Company property, then as the 
Snow prospect, and later as the White mine, is 
located on Rogers Creek about 2000 feet northeast 
of the Womble mine. According to Conley (1962a) 
"The ore body is contained between the Glendon 
fault on the southeast and a secondary reverse 
fault on the northwest." Prospecting by open cut 
has been carried out for a total length of approxi- 
mately 2000 feet most of which is on the south- 
west side of Rogers Creek; recently, however, 
prospect pits have been extended a considerable 
distance northeast of Rogers Creek. The pyro- 
phyllite body is lenticular in outline and has a 
cleavage that strikes northeast and dips at an 
angle of 60 to 70 degrees to the northwest. 

The mineral body is found in an acid volcanic 
fragmental rock. The footwall is an acid volcanic 
breccia with fragments up to 3 or 4 inches in 
diameter. The hanging wall is a medium textured 
acid tuff. Chloritoid and chlorite are present in 
small amounts as minute grains. The pyrophyllite 
is yellowish to white in color and of the compact 




* ■.'-»■; 

1 ! 1 

\ 7 

■? ; 

3* "TIT) 

A. Mill 

B. Open Pit Mine 

Plate 3. Glendon Pyrophyllite Company 


foliated variety. Some of the best pyrophyllite 
shows the fragmental texture which was charac- 
teristic of some of the original rock before re- 

Pyrophyllite has been exposed in an open cut 
along strike for some 500 feet. The northeastern 
end of this pit near Rogers Creek is about 150 
feet wide at the top and 50 to 60 feet deep. Both 
northeast and the southwest of this well devel- 
oped part of the open cut all the indications point 
to promising amounts of good pyrophyllite. This 
property appears to contain a large body of pyro- 

Jones Prospect 

A little more than a mile northeast of the 
Reaves mine is the Jones prospect which was 
opened on land formerly belonging to the late 
A. J. Jones but now reported to be a part of the 
Hancock estate. An open cut about 100 feet long 
and 2 to 6 feet deep was opened on the northeast 
slope of a small hill, just above a small stream. 
The few surface exposures present indicate that 
the rock in this area is highly sheared. Good 
pyrophyllite, somewhat foliated and discolored, 
and masses of sericite schist containing chloritoid 
are to be seen along this pit. The size of the de- 
posit could not be determined from the amount 
of prospecting done. Enough can be seen to indi- 
cate that the prospect may have promise of be- 
coming an important producer of pyrophyllite. 

Currie Prospect 

About one-half mile northeast of the Jones 
prospect and near the point where State Road 
1620 crosses the county line, prospecting for py- 
rophyllite was done on the farm of C. L. Currie 
several years ago. When first opened the pits 
showed some signs of pyrophyllite, but now they 
are more or less filled up and overgrown to the 
extent that little or no pyrophyllite can be seen. 
It will take considerable prospecting to determine 
if pyrophyllite of value is present at this locality. 

Ruff Prospect 

The Ruff prospect, according to Conley (1962a) 
is located about 1.5 miles southwest of Hallison. 
The mineralized zone averages from 6 to 15 feet 
wide at the center, but narrows to the northwest 
and southeast, and finally dies out along strike in 
these directions. The mineralized zone which can 

be traced for about 180 feet occurs in a fault zone 
which strikes N. 20° E. and dips northwest at 
about 80 degrees. The southeastern limb of the 
deposit is displaced to the northwest by a cross 
fault which strikes N. 45° W. and dips to the 
northeast at about 75 degrees. 

Hallison Prospect 

Less than a mile southwest of Hallison is a 
small body of pyrophyllite schist that was dis- 
covered while prospecting for gold. At this point, 
several shallow pits have been dug along a quartz 
vein. The rock in contact with the quartz is a 
sericite schist containing varying amounts of py- 
rophyllite. The prospect is located in the shear 
zone of a northeast trending fault in felsic tuffs. 
The prospect pits do not reveal the presence of 
much pyrophyllite but the geologic setting is 
correct for a workable deposit. 

Standard Mineral Company 

Beginning about 1.5 miles southwest of Rob- 
bins on Cabin Creek and continuing in a south- 
west direction for a distance of some 5 miles is a 
band or zone of pyrophyllite on which the most 
important mine in the State is located. The rocks 
along this zone consists of an acid volcanic tuff. 
The strike varies from N. 35° to 40° E. and the 
dip varies from 50 to 70 degrees to the northwest. 
Pyrophyllite schist crops out at a number of 
points along this zone but only two deposits are 
known to be of commercial value at present. 

The property of the Standard Mineral Company 
is located about 2.5 miles southwest of Robbins 
and about 1.5 miles south of the Norfolk Southern 
Railway. Pyrophyllite is said to have been dis- 
covered on this property about 1888 when in the 
course of gold mining operations a drift was 
driven into a hillside. The vein encountered at 
that time was only about 10 feet wide and little 
effort was made to work it. In 1918, Mr. Paul 
Gerhardt gave a neighbor permission to haul 
cross ties across his property. The wagon wheels 
brought up a fine white material which proved to 
be pyrophyllite, from a zone of pyrophyllite and 
pyrophyllite schist some 150 feet wide. 

During 1919 some pyrophyllite was mined 
from open cuts and shipped to Charlotte for grind- 
ing. This did not prove economical and in 1920 a 
shaft was sunk to a depth of 90 feet on a lens of 
pyrophyllite about 14 feet wide and a small 
grinding mill was built on the property. Under- 


A. Mill 

t. ' 

B. Open Pit Mine 
Plate 4. Standard Mineral Company 


ground exploration and development work showed 
that to the northwest there was a body of pyro- 
phyllite 30 feet wide. About 1925 a shaft 200 feet 
deep was sunk in barren ground adjacent to this 
30 foot vein of pyrophyllite and a more modern 
grinding mill was built. Later a modern two com- 
partment shaft was sunk to a depth of 650 feet 
in the footwall of the deposit at a point some 700 
feet northeast of the first two shafts, and a mod- 
ern grinding mill was built on the Norfolk South- 
ern Railway 1.5 miles away. This shaft and mill 
are currently being used in mining and grinding 

This pyrophyllite body as it is known today be- 
gins on Cabin Creek just south of the old Cagle 
gold mine and extends southwest for a distance 
of nearly a mile. The most important part of this 
body is on the southwestern end and consists of 
some 2000 feet along the surface. The mineralized 
zone is about 200 feet wide and lies along the 
Robbins fault in a zone of complicated reverse 
faulting. In places this faulting has repeated the 
pyrophyllite zone, making the minable pyrophyl- 
lite body as much as 150 feet wide. The north- 
eastern half of the deposit is offset to the north- 
west by cross faulting. 

The deposit occurs in a medium to fine-textured 
felsic tuff which has been strongly sheared and 
possesses a well defined cleavage which strikes N. 
20° to 30° E. and dips from 50 to 70 degrees to 
the northwest. Underground operations show the 
hanging wall to consist of 75 to 100 feet of silici- 
fied tuff grading into an unaltered tuff. On the 
footwall side, the rock consists of a silicified tuff 
about 110 feet wide which gradually grades into 
an unaltered tuff. For a number of years, mining 
has been carried out both by underground and 
open pit operations. The pyrophyllite taken from 
this mine is in general of a high quality. The im- 
purities consists of small lenses of silicified tuff 
and numerous small quartz veins. Varying 
amounts of sericite and an occasional grain of 
chloritoid are found around the borders of the 

Tucker and Williams Pits 

The Tucker and Williams pits are located on 
the Robbins fault about two miles southwest of 
the mine of the Standard Mineral Company. Pyro- 
phyllite is exposed in both pits which are about 
500 feet apart. The Tucker pit is on the north 
and the Williams pit is on the south. Pyrophyllite 

has been developed in both pits along two parallel 
shear zones some 20 to 25 feet wide. Good grade 
pyrophyllite is exposed in the shear zones, while 
the material bordering the good pyrophyllite is 
a highly siliceous sericite schist that is badly iron 
stained. The shear zones and the cleavage in the 
pyrophyllite strike N. 30° to 35° E. and dip steep- 
ly to the northwest. The pyrophyllite bodies ex- 
posed in the southern pit lie to the northwest of 
the strike of those in the northern pit, indicating 
that the mineralized zones have been offset by 
cross faults. The country rock is a highly silici- 
fied and sericitized fine-grained felsic tuff that has 
been badly crushed and sheared. 

Sanders Prospect 

About 5 miles southeast of Star and a few 
hundred feet from the point where Cotton Creek 
enters Cabin Creek, on a farm formerly owned by 
Mrs. Bettie Sanders but now the property of 
Harry Lemons, is an outcrop of pyrophyllite that 
can be traced for about 800 to 1000 feet along 
the surface. Pyrophyllite is found, about 500 feet 
west from the house, on a prominent ridge that 
extends back from the creek 500 to 800 feet in a 
northeast direction. 

The country rock is a medium to fine textured, 
felsic volcanic tuff with a well developed cleavage 
which strikes N. 30° E. and dips 40 to 50 degrees 
to the northwest. Numerous small quartz veins 
cut the country rock at all angles. Associated with 
these small quartz veins and scattered through 
the country rock are varying amounts of pyro- 
phyllite, chiefly of the radiating variety. Small 
amounts of flake and foliated pyrophyllite are 
also present. In 1922 the writer collected some 
excellent specimens of radiating pyrophyllite from 
a small pit on the southeast slope of the hill. 
Associated with this pyrophyllite were veins of 
diaspore 2 to 3 inches thick. The old pit has 
been filled up and is grown over and no longer 
available for collecting. 

On the point of the ridge to the southwest end 
of the property near the creek are two old pits. 
These pits which are some 5 to 10 feet deep and 
10 feet long are said to have been gold prospects. 
Both show small amounts of pyrophyllite which 
is of the radiating variety and badly iron stained. 
On the southwest slope of the hill, just above the 
creek, is a trench 2 or 3 feet deep and 150 feet 
long that trends in a N. 20° W. direction. This 
trench shows very little pyrophyllite. 



Ammons Mine 

Pyrophyllite deposits that have been prospected 
and/or mined occur at 5 localities in Montgomery 
County. One of these known as the Ammons mine 
is located in the northeast corner of the county 
a short distance southeast of Asbury on U.S. 
Highway 220 to State Road 1340 which is also 
marked, "Mine Road." Follow "Mine Road" 
about one-half mile to the corner of a field where 
two unimproved roads may be seen. One of these 
leads in a direction a little east of south and ends 
at a distance of about 2500 feet at the Ammons 

The Ammons mine, now worked out and aban- 
doned, consists of an open cut approximately 1500 
feet long that strikes in an over-all direction of 
about north 40 degrees east, and varies in depth 
from 10 to 25 or 30 feet. All indications are that 
a fair amount of good pyrophyllite, highly foli- 
ated, was obtained from this mine. The pyrophyl- 
lite appears to have occurred as lenses 1 to 3 feet 
wide and 10 to 15 feet long associated with a 
cherty to siliceous rock. Before mineralization 
this rock was a normal felsic tuff of volcanic 
origin. At least the rock surrounding the mine pit 
is a felsic fragmental material of volcanic origin. 

The only good pyrophyllite seen on this prop- 
erty is a lense of undetermined width and about 
50 feet long that is partly exposed in the bank of 
a small stream at the northeast end of the open 
cut. Nothing was seen to indicate why this lens 
was left undisturbed. 

North State Property 

About 1500 feet along strike to the northeast 
of the Ammons mine is a pyrophyllite deposit 75 
to 200 feet wide and 1000 to 1200 feet long that 
is owned by North State Pyrophyllite Company. 
It may be reached by following "Mine Road" 
about one-half mile from its intersection with 
U. S. Highway 220 to the corner of a field, and 
then taking an unimproved road that leads in a 
direction a little south of east. This unimproved 
road ends at the deposit which is about 1500 feet 
from "Mine Road." 

The deposit is in the form of a ridge that rises 
20 to 40 feet above the elevation of the surround- 
ing countryside and trends in a north 40 degrees 
east direction. The ridge contains four knobs or 
knob-like masses 75 to 150 feet wide and 150 to 

250 feet long that rise to elevations of 10 to 20 
feet above the remainder of the ridge. These 
knobs are composed largely of good pyrophyllite. 
Rock outcrops are not abundant in the sags be- 
tween knobs but those found were composed 
largely of good pyrophyllite. 

The property has been core drilled but records 
of the holes are not available. A marker at one 
hole indicated a depth of 50 feet. If as indicated 
from the outcrops available, this ridge contains 
good pyrophyllite throughout its length and the 
pyrophyllite extends to a depth of 50 feet below 
the general surface, the deposit contains a large 
tonnage of good material. The impurities observed 
were limited amounts of chloritoid, some vein 
quartz and some iron stain which appears to be 
most abundant near some old pits and shafts that 
were dug during prospecting for gold. 

North State Property 2 

About three miles southeast of Abner is an- 
other interesting deposit of pyrophyllite that was 
prospected to a limited extent several years ago 
by North State Pyrophyllite Company. This de- 
posit may be reached by starting at the point 
where State Road 1312 crosses 1311. From this 
point follow State Road 1312 south for a distance 
of seven tenths of a mile to an unimproved road. 
Follow this road for three tenths of a mile in a 
southeast direction to a quartz ridge that shows 
signs of having been prospected. Then follow 
the quartz ridge in a general northeast direction 
to a prominent hill. 

This hill trends about north 40 degrees east, 
has a maximum width of about 300 feet, a length 
of between 400 and 500 feet and rises more than 
50 feet above the general elevation of the sur- 
rounding countryside. This hill contains some un- 
altered rock but appears to consist largely of py- 
rophyllite. A prospect pit or quarry was started 
some years ago on the northwest side near the 
foot of the hill and developed at right angles to 
the strike of the cleavage of the pyrophyllite, for 
a distance of about 20 feet, all in good pyrophyl- 
lite. Had the quarry been continued to the center 
of the hill a quarry face at least 40 to 50 feet 
high would have been developed. The pyrophyllite 
contains an excessive amount of chloritoid which 
apparently accounts for not developing the de- 
posit. Except for excessive chloritoid this is a 
promising deposit of pyrophyllite. 


Cotton Stone Mountain 

Cotton Stone Mountain is located about 4 miles 
almost due north of the center of Troy and less 
than one-half mile west of State Road 1312. Pyro- 
phyllite has been known to occur in the general 
vicinity of Troy since Emmons published his 
"Geological Report on the Midland Counties of 
North Carolina" in 1856. Many textbooks also 
carry references to pyrophyllite on Cotton Stone 

This mountain is a prominent hill that rises 
gradually to a height of some 200 feet above the 
neighboring stream valley. The hill consists of 
two prominent points or knobs with a sag between 
them, producing a saddle. The country rock is an 
acid volcanic tuff with a definite cleavage that 
strikes north 45 to 55 degrees east and dips 50 to 
70 degrees to the northwest. Numerous quartz 
veins are found throughout the mountain. 

Pyrophyllite, chiefly of the radiating variety, 
occurs abundantly on this hill. The numerous 
quartz, veins present have made mining of this 
pyrophyllite uneconomical. The mineral body is 
elongated in a northeast-southwest direction with 
a length of some 1500 to 2000 feet. On the south- 
west, and more prominent point of the hill, two 
or three prospect pits have been dug, presumably 
for gold as they are all along quartz veins. In 
these pits and on the dumps much pyrophyllite 
may be seen all of which is badly iron stained. 
The excessive quartz and great amount of iron 
stain have apparently discouraged prospecting for 
pyrophyllite on Cotton Stone Mountain. 

Standard Mineral Company 

Standard Mineral Company is developing a 
promising pyrophyllite deposit about 1.5 miles 
northwest of Wadeville. This deposit may be 
reached by going west of Wadeville on State Road 
1134 to the intersection with State Road 1135, 
and then north along State Road 1135 a distance 
of seven-tenths of a mile to a private road that 
leads about north 45 degrees west, a distance of 
about three-fourths of a mile and ends at the 

The country rock of the region is a f elsic frag- 
mental rock of volcanic origin. The pyrophyllite 
deposit as explored is about 300 feet wide and 
500 feet long. The pyrophyllite 'and enclosing rocks 
have a cleavage that strikes about north 40 de- 
grees east and dips steeply to the northwest. The 

deposit appears to contain a high percentage of 
good pyrophyllite. A small amount of chloritoid 
is associated with the pyrophyllite and some 
quartz veins are also present. The pyrophyllite 
varies from massive to foliated, with the foliated 
variety being more abundant. Near the north end 
of the deposit, as now developed, there is some 
red clay present as one or more zones in otherwise 
good pyrophyllite. On the footwall side near the 
northeast end of the body is some very pure seri- 
cite. This is a promising deposit that appears to 
contain a large tonnage of high-grade pyrophyl- 


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